The number of active email users grows every year. In 2021, it reached 4.1 billion , and by 2025, it is expected to grow to 4.5 billion. With emails, we communicate, work, sign up for services, receive personalized offers, and get information about our online orders.
In this article, we will discuss why emails remain one of the principal communication channels and are integral to most digital marketing strategies. Let’s discover how to launch an email marketing campaign: create a list of recipients, build an engaging message, and measure the results.
What is email marketing and why do we use it
Email marketing is a communication channel through which you can send bulk emails to the intended audience. It builds direct communication between the brand and its customers.
Email marketing as a communication channel has a wide array of important competitive advantages:
- High ROI. For every dollar spent, email marketing returns $44 .
- Personalization. Emails establish direct contact with the client, which significantly increases campaign effectiveness.
- Repeat sales. Retaining customers is always cheaper than attracting them. Emails help persuade users to visit the website and buy again.
- Largest potential customer base. As we said before, the number of email users is over 4 billion, which is several times higher than the audience of Facebook.
- Universal nature. This communication channel is used by all types of businesses worldwide to drive sales, inform and engage audiences, and build communities.
Email marketing goals
Email marketing is an effective tool for many promotion tasks. Let’s discuss some of them:
- Building relationships and trust. Emails are great to communicate directly with existing and potential clients. You can nurture their trust and improve your brand image by sharing reviews and testimonials from real people or providing unique offerings and useful tips. This will prove that your business is trustworthy and convince people to visit your site for more information.
- Increasing brand awareness. Emails are often used to tell potential clients about your company. The more often your brand name appears in their inbox, the more likely they will remember and recall it at the right time. This leads to an increase in brand loyalty and, as a result, in profits.
- Increasing traffic. Links in emails help increase website traffic. But this only works if the offer is relevant to readers and the call-to-action is engaging.
- Promoting content. Email marketing works great for driving traffic to social media posts, blog articles and other website pages.
- Promoting products and services. Emails help you persuade subscribers to make a purchase. You can inform them about upcoming sales and offer them personalized discounts. This technique is excellent for convincing customers who have already shown interest in your products or services to make their first purchase.
- Re-engaging inactive subscribers. Emails could be used to remind your subscribers about yourself and reactivate them — awaken their interest and persuade them to make another purchase.
- Automating routine tasks. You can configure automatic replies to various actions, for example, send a confirmation letter to new subscribers. Automation will allow email marketers to focus on more important tasks.
Types of email campaigns
Depending on campaign goals, there are four main types of emails:
- Informational emails. Such letters are not meant to drive sales. They are supposed to increase brand awareness and loyalty, as well as introduce subscribers to products and services. The most popular examples of informational emails are newsletters, polls, tips, instructions, product reviews, and blog articles.
- Promotional emails. These emails are aimed at selling products and services. They are supposed to persuade subscribers to make a purchase—they are brief and contain a simple call-to-action. In a promotional email, you can let subscribers know about sales, seasonal promotions, or discounts.
- Transactional or trigger emails . These emails are usually sent automatically for a specific event—for example, a purchase or registration on a website, billing notification, booking reminder, etc. They allow clients to receive an instant response and email specialists or support teams to automate processes and save resources on routine tasks.
- Reactivation emails . These emails are sent to subscribers that have not been active for some time. With their help, you can either resume interaction with customers or, if they are not interested in your offers, stop communication and remove them from the mailing list. This helps you minimize the risk of harming the reputation of the IP address and also helps you control the marketing budget by not spending money on inactive subscribers. But most importantly, it can help revive subscribers and bring additional conversions and profits. Usually, reactivation emails contain personal discounts, gifts, and bonuses—something to kindle the subscriber’s interest.
Getting started with email marketing
Email marketing consists of several important steps. Let’s find out how to launch a successful email campaign.
Selecting an email service
The first thing you should do is decide how to send your emails. Using your personal email address is a very bad idea, because:
- You cannot send a large number of letters. For example, Gmail allows sending up to 500 messages per day to a maximum of 500 recipients.
- Emails from personal addresses are very likely to go to spam . Your customers might not even see your emails.
- You will not be able to analyze the effectiveness of your campaign. You will not be able to understand which letters were successful, who opened them, who clicked on the link, etc.
- There is no possibility to customize emails. Most email templates with buttons, pictures, and banners are available only through special services.
- There will be no unsubscribe button , which may violate laws in some countries.
Therefore , you should select an email service provider for your business. It will allow you to send bulk emails and analyze campaigns in one place, as well as automate routine tasks at a low cost. There are lots of email services with the seemingly same functions. You should go through each one to understand which one is suitable for your particular business needs.
Regardless of the goals you pursue, the capabilities of the service must include the following:
- Import of contacts. You should be able to upload a list of contacts in different formats: csv, txt, xls, xlsx . Adding every contact manually takes a lot of effort and is very time-consuming, especially if you are working with a large client list.
- Contact segmentation. This function allows grouping subscribers by different characteristics. This will help tailor your emails to specific audiences, so you do not send the same letter to everyone on a list, especially to those who may not be interested in your offer.
- Visual editor. The email should be appealing and engaging. You want your service to provide a visual editor to create attractive and functional emails. The best option is the block editor with a library of templates and the ability to upload your own HTML code.
- Personalization. The service must be able to automatically include subscribers’ personal data in the email, for example, their name, company, or bonuses. This can help increase email open rates.
- Scheduled emails. This feature allows you to schedule an email for a specific time and date, which is helpful if you want to send your messages during the holidays or weekends.
- Analytics. To evaluate the effectiveness of an email campaign or a particular email, you need to have access to statistics and analytics. This feature allows you to track the number of sent and delivered emails, and find out their open and click-through rate. This way, you will know which campaigns failed and which were more successful than others, and adjust your next steps accordingly.
- Unsubscribe button. Every service should support adding an unsubscribe button or link. Without it, your email risks ending up in spam.
- Automated emails. The email service should have an API interface and API documentation, which allow sending emails in response to users’ actions on the website or in the CRM system.
All these features will not only make your work with emails easier but will also help avoid possible legal issues or loss of trust. The service will help you create appealing emails in several clicks and analyze important metrics: open rate, click-through rate, unsubscribed users, etc.
Here are some popular services that support the above mentioned features:
Setting goals is an essential stage of every email campaign. With accurately set goals, you can figure out the required steps and analyze your progress towards them. They may vary depending on your business needs, but each goal should be:
- Clear . You need to think about specific results and benefits for the company and target audience.
- Limited in time . You should set a specific period for achieving the goal—this will help control the process.
- Significant . Try to determine how your business will benefit after achieving the goal. If the value is insignificant, it is probably a waste of resources.
- Achievable . Be realistic—plan a budget accurately, considering all available resources. Do not pursue unattainable goals.
- Measurable . Decide on specific criteria to evaluate the results. Determine key performance indicators and check them constantly to make sure your efforts help achieve the goal.
|Poorly set goal ❌||Proper goal ✅|
|Increase website traffic with the help of email marketing.||Reduce the cost of paid traffic by increasing traffic coming to the site from email by 30% by the end of the year.|
|Increase company awareness via email marketing.||Raise the level of awareness about the product among the 20-40 year old audience to 25% using emails during the first year after market launch.|
With the right goals set, try to figure out how to achieve them. Defining smaller KPIs could be quite helpful. Smaller KPIs not only help complete preliminary tasks but also select the shortest route towards the main goal.
Collecting your email database
There are numerous ways to convince users to subscribe to your emails: discounts on the first purchase, free trials, helpful checklists, bonuses, and much more. Let us analyze some of the popular methods of collecting your email database.
Users should always have an option to refuse to sign up for emails. Therefore, make sure your subscribers have given explicit consent to receive your emails. You can get permission to process personal data and send emails through written consent, using a checkbox in sign-up forms, or through double opt-in. Otherwise, your emails risk ending up in spam folders or reaching uninterested users.
How can you get subscriber data?
- Registration forms. Most websites have a special field for the email address in registration forms. You can use it to collect information for email campaigns.
- Order forms. When users place an order on the website, they enter an email address to receive order details. You can add a checkbox to suggest signing up for emails.
- Feedback forms. Sometimes users ask questions or leave comments on the website and enter their emails to get answers. Here you can add an option for receiving emails.
- Lead magnets. You can offer valuable content—ebooks, free templates, checklists, training materials, webinars—in exchange for the user’s email. This is one of the most popular and effective ways to collect contacts, as it is much easier for customers to leave an email if they are rewarded for doing so.
- Pop-up on the website or blog. Try placing a pop-up window or a small banner at the bottom of the page that briefly describes how subscribers can benefit from your emails.
Do not buy contact information. This is prohibited by law since users did not consent to the processing of their data.
Purchased or downloaded email lists are very likely to harm your campaign and even the company as a whole. Apart from it being illegal, the efficiency of emails will be close to zero—your emails will just end up in spam. As a consequence, Google can put your domain on the “black list” and apply sanctions, which will harm the website even more. Therefore, it is better to spend resources on collecting your own email list. This way, you can be sure that your emails will go to interested customers who have agreed to receive them.
The collected database should be divided into segments by different parameters. This makes it possible to send relevant offers to specific groups of subscribers based on their needs and preferences. Targeted messages are much more effective, which allows for higher open and conversion rates.
Here are the most popular segmentation criteria:
- Demographics. Segmentation by age and gender is usually used in ecommerce but not limited to it. For example, men are frequently offered to buy car accessories or hand tools, while women are offered cosmetics or jewelry. You can also use this segmentation to adjust the visual design and tone of voice of emails.
- Location. This segmentation parameter is used by companies that depend on physical location: restaurants, stores, event ticketing businesses, or job sites.
- Interests. Usually, segmentation by interests implies division by the type of content that the user wants to receive: promotional emails, digests, news, or all together. You can use other criteria as well. In the B2B sector, for example, you can segment your audience by their business niche, size of their company, or product category they are interested in. To learn about users’ individual preferences, let them create personal profiles or bookmark products on the website.
RFM (recency, frequency, monetary value).
Subscribers can be easily divided into the following groups:
- New users. You can send them a chain of welcome letters, appealing offers, or training materials.
- Inactive users. Send them various bonuses, gifts, and personal discounts to motivate them to purchase again.
- Regular customers. They usually get emails with promotions and discounts, information about new products, or useful content.
- VIP clients . These subscribers are often offered exclusive offers.
- “Dead” clients. These subscribers have not interacted with the company for over a year, but their contact information remains in your database. You can send them reactivation emails with discounts, digests, or news about your company or products.
In fact, you can segment your database according to any criterion that is important for your company. The main thing is to understand what the grouping will bring to the business.
Creating your email
The next step is to create the email itself. Pay attention to every element: name and address of the sender, subject, preheader, and body of the message.
Name and address
The sender’s name is one of the things that subscribers pay attention to. Users need to understand who sent the email to decide whether to open or ignore it. Make sure your subscribers understand which company it came from.
Try to make the sender name no more than 20 characters so that it will be fully displayed on any device.
What can you use for the sender’s name? Let us consider several options:
- Company name. This is the most popular option. It works well if you send one email to the entire contact list.
- Employee name with a company name. This is a great way to show that the email comes from a real person and not from an automated program. This approach can help you win followers and build loyalty to the company. If you have several types of emails (technical ones, digests, news, etc.), try using different names for each of them. Should you select this approach, try to work out the author’s writing style, adjust the content, use the appropriate signature, and respond to the replies of subscribers.
- Just a name. This option is usually used for promotional emails of a personal brand because it shows that a real person is communicating with the subscriber. Large companies may use this option only if it is the name of a popular expert in the niche. And keep in mind that this approach may confuse readers because they simply may not understand who the email comes from and, as a result, will not open it.
Get rid of noreply in the sender’s name. Users often delete such emails because nobody wants to receive letters from a robot. Instead, use the name of a real person who works for your company.
Only use corporate email addresses. As mentioned before, in most cases bulk mailings from public emails end up in spam. You may use a public email only for test emails or for a small contact list.
✅ Corporate address: @domain.com
❌ Public address: @gmail.com, @live.com, @yahoo.com, etc.
Also, try to avoid changing the sender’s address too often—it should be recognizable and distinctive.
Subject and preheader
The second thing users look at is the subject. This is the heading of the letter which gives a brief description of what an email is about and differentiates it from other emails in the inbox.
There is always a preheader next to a subject. It clarifies the subject and convinces the subscriber to open the letter.
Here are some basic guidelines you should follow when creating your subject and preheader:
- Personalize emails . Emails with personalized subjects and preheaders are 26% more likely to be opened . You can include the name of the recipient, their city of residence, amount of available bonuses, etc.
- Keep it short . You want to be sure that the subject will be fully displayed on any device. Avoid creating topics longer than 40 characters. Think over every word to grab the user’s attention and convince them to open the email.
- Add a call to action . Direct calls to action tend to increase the open rate of the letter. The call to action can be placed both in the subject and in the preheader. This works especially well for promotional emails.
- Avoid clickbait and spam . Get rid of aggressive wording, and do not use caps or redundant exclamation marks, since it may trigger spam filters. Even if such a letter does get to the inbox, it is unlikely to be read.
- Use emojis. They help your emails stand out from others and attract the user’s attention. But do not overuse them, as it may also be considered spam.
- Do not mislead. If you promise something in the subject, make sure to fulfill it in the body of the email. If you fail to do so and the subject is irrelevant to the rest of the content, this will undermine trust and users will simply delete the message or report spam.
Pay as much attention to the subject and preheader as possible, because they determine whether the user will open the email or not.
The body is another essential part of the email. In it, you should fully reveal the topic, offer your services, and convince subscribers to perform further actions—visit the site, make a purchase, register, etc.
When you are building an email body, try to keep consistency with the website—use corporate colors, tone of voice, distinctive graphic elements, etc. This way your emails will be easy to recognize and differentiate.
Speaking of email design, a single-column layout is the best option in most cases. This way your email will have a straightforward structure—users will not have to jump between columns and it will be easier to keep their attention.
Also, pay attention to the quality of your copy. Adjust the structure of the text and divide it into semantic blocks and paragraphs to make your email readable. Write as clear and simple as possible—avoid vague assertions, complex terms, and long sentences.
And keep in mind that users do not like longreads. So keep it short. Of course, it all depends on the topic and what you have to offer. For example, an email with a selection of useful articles or tips can be quite sizable. But promotional emails should be as brief as possible. Ideally, it should take approximately 11 seconds to read.
Emails should always contain one simple call to action. Raise the interest of your readers, keep their attention focused, and guide them towards the CTA. It is always a good idea to add one conspicuous button for the call to action. But if the email format needs several buttons, make sure readers can differentiate between them and that the primary one stands out from the rest. For example, fill the primary button with color but leave the rest transparent with only the borders outlined.
Do not forget about the footer of your email. It should contain important information, for example:
- company contacts (address, work schedule, social networks)
- details about the person who sent the email
- links to mobile apps, site categories, or important pages
- a phrase that explains why a person has received an email
But the most important thing to include in the footer is the unsubscribe button or link. It must be in the same language as the main copy. Do not send emails without it and do not try to hide it by merging its color with the background or minimizing the font.
It may be a good idea to duplicate the unsubscribe link in the email header.
Why are we talking so much about the unsubscribe button? Because it helps build trust in your emails. When users have an option to easily unsubscribe at any time, they do not complain about spam. This contributes to your good reputation in the email service and helps avoid drops in performance. Besides, this way you can clean your mailing list from uninterested or inactive users.
Also, the footer can contain information about where you got the subscriber’s contact information from.
Another important note: emails should not exceed 102 KB. If it is too large, Gmail may crop it and readers will not see important parts of the email, which will affect conversion. This also significantly increases the risk of getting into spam.
Last but not least, pay attention to responsive layout. Responsive emails can adjust to fit any display or device—the text and the pictures will be of the optimal size, and there will be no horizontal layout shift. You can use special tools like Litmus or Email on Acid to see how your email is displayed on different devices.
Emailing schedules may vary from company to company and depend on many factors: target audience, business niche, email content, etc. According to a study, most emails are sent from 5:00 to 10:00 . The highest open rate is usually in the afternoon, from 13:00 to 14:00, and in the evening, from 20:00 to 22:00.
Studies also show that some days are better for sending particular emails than others. For example, Monday works better for polls, and Friday for entertaining content and promotions. Business emails have higher open rates from Tuesday to Thursday.
But no matter what the statistics and research show, you should analyze your audience and determine the best time for your email campaigns. To figure out the optimal time, you can do A/B testing—divide your mailing list into several groups and send emails at different times. Run several A/B tests, define the time that works best for your niche, and adjust your campaigns accordingly.
Regardless of the test results, you can allow your subscribers to choose the frequency. In the subscription form, let them select how often they want to receive your emails, for example, daily, weekly, or monthly.
Dedicate some time to identify the points of interaction with your audience. Let them choose the content they need. Some users may be interested in discounts or advertisements, others in blog articles or webinars. This will help you plan your content and determine the frequency of emails.
And, of course, if your company operates in several time zones, do not forget to take it into account. Customers should receive emails at a time that is appropriate for them.
Automating processes with email marketing
Email marketing can help automate some processes, saving time and budget. To set up automation, you need to define certain triggering events that will initiate a chain of emails to the user. You can configure and schedule multiple chains with a variety of letters for different triggering events:
- confirmation after registration on the website
- confirmation after responding to a survey
- reminder about an abandoned shopping cart
- information about an order or purchase
- subscription to the newsletter
- follow-ups after events or webinars
- notification about the change of password or contact information
- congratulations on birthdays or anniversaries
- onboarding messages with instructions on how to use the product
- company’s news
- promotions, special offers, and reactivation campaigns
Email chains can be used in any niche for companies to constantly stay in contact with their audience. This is especially important in ecommerce and B2B because of a long transaction cycle and high competition.
The undisputable benefit of automated emails is the speed of communication with subscribers. This approach helps build long-term relationships with customers and increase their loyalty.
Evaluating the success of email campaigns
To figure out which campaigns are more successful than others and what can be done better next time, you should assess the effectiveness of your emails. There are several performance indicators you should track:
Deliverability —the percentage of emails that have reached recipients’ mailboxes. You want this indicator to approach 99%. Low deliverability is a serious problem and indicates that you may have been blocked.
How can you improve this metric:
- Remove inactive subscribers from the mailing list
- Remove emails with hard bounces
Open rate —the percentage of users who opened an email. It indicates how well your email grabs subscribers’ attention. 20% is considered to be a fairly good open rate.
How can you improve this metric:
- Try different sender names, addresses, or subject lines
- Try another day and time to send emails
- Remove inactive addresses from the mailing list
Click-through rate (CTR) —the percentage of users who clicked on the CTA button or link placed in the email. A low CTR means that subscribers are not interested enough to follow the link.
How can you improve this metric:
- Review your offer to make it more valuable to subscribers
- Fix the structure of the text to make it more straightforward
- Run A/B tests to find convincing calls to action
Unsubscribed users —the number of people who unsubscribed from receiving emails. Some common reasons why users decide to unsubscribe are: they receive too many emails, have lost interest, or are unsatisfied with something.
How can you improve this metric:
- Check the frequency of your emails
- Make sure your emails deliver value to your target audience
- Build trust and avoid making promises you cannot keep
Bounces —the number of messages that did not make it to subscribers’ mailboxes. A high bounce rate may indicate that either your address has been blacklisted by users or emails are being sent to inactive email addresses. Try to keep your bounce rate below 0.5% because some email service providers block domains with a bounce rate higher than 1%.
How can you improve this metric:
- Check if your domain is on blacklists
- Make sure to meet the conditions and requirements of email service providers
- Exclude users that refused to receive your emails
- Limit the emailing frequency for inactive customers
- Configure double opt-in subscription confirmation
- Add the unsubscribe button
- Get rid of spam words in the text
Conversion rate —the number of users who converted from the email: purchased, downloaded your content, subscribed, etc.
How can you improve this metric:
- Configure email chains to warm up and retain subscribers
- Personalize emails and offers
- Encourage conversions with discounts, free shipping, bonuses, or gifts
- Let users choose the frequency and type of content they receive
- Optimize landing pages your emails refer to
Track these indicators constantly to assess the effectiveness of your campaigns and make quick adjustments if necessary.
Profitability of email marketing
As I have mentioned before, email marketing is one the most cost-efficient marketing tools that can bring considerable returns with minimal investment. The cost of launching an email campaign depends on many factors: selected provider, size of the contact list, and required functionality. This means that the exact cost varies for every campaign and directly depends on set goals.
Let’s take a look at some different email services and their monthly pricing plans:
- SendPulse: free up to 500 subscribers, up to $840 for 500,000 subscribers
- MailChimp: free up to 2,000 contacts with limited functionality, $1,190 for 200,000 contacts
- Campaign Monitor: $9 for 500 subscribers, up to $299 for 50,000 subscribers
- GetResponse: from $10 for 1,000 contacts and up to $580 for 100,000 contacts and advanced features
- UniSender: from $7 for 500 contacts and up to $1,482 for 500,000 contacts
- eSputnik: about $2 for 1,000 contacts and $450 for 250,000 contacts
- Reply.io: from $70 for 1,000 contacts and up to $120 for an unlimited list
Once you have chosen a platform, decide how much you can spend to collect email addresses. This cost includes copywriting, banner design, creating lead magnets, ads, etc. With all that in mind, you will know the approximate cost of your email campaign.
Note that email marketing is a long-term tool. Do not expect lots of profits in the first few months. If your email campaign pays off in two years , consider it a good result. Nevertheless, it is a remarkably effective investment: every $1 spent in Google AdWords generates $2 revenue, while email marketing can return $44 .
Email marketing is a very extensive topic and we can go on talking about it. But let’s point out several basic tips which will help you avoid common mistakes and improve the performance of your email campaigns:
- Comply with local regulations . Depending on where the users that you provide services or sell goods to are located, adhere to the laws and rules that apply: the GDPR for the UK and EU, the CAN-SPAM act in the US, etc. For instance, the GDPR requires using two-step verification for subscription and clarifying how user data is being stored and transmitted.
- Clean up email lists regularly . Any database becomes obsolete over time—some users unsubscribe, and others stop opening your emails. Such subscribers do not bring any benefit and only worsen the statistics. Cleaning up your contacts will lower the cost of your campaigns, improve performance metrics, and reduce complaints.
- Welcome new subscribers . Users expect to receive an email from you after subscribing. Do not hesitate to demonstrate your appreciation and attention to every new subscriber. Make an introduction to products and services and tell them about the benefits. You can even create a chain of welcoming emails to improve engagement.
- Send emails regularly . Choose a certain frequency and send emails repeatedly. But keep in mind that sending emails too often is also bad—users will not appreciate it and will unsubscribe or complain about spam.
- Check emails for spam . If you use spam words or an excessive number of exclamation marks in the subject line, email deliverability will deteriorate.
- Test your emails . Check how emails look on different devices and make sure your readers can interact with every element.
- Segment your audience . This will increase the conversion rate because targeted emails are more effective than bulk.
Email marketing is an effective communication channel that can help build brand loyalty, generate traffic, and increase sales. Let’s run through every step of an email marketing campaign one more time:
- Select an email service. Without one, you will not be able to send a large number of emails and monitor their effectiveness.
- Set goals . Define measurable, achievable, clear, and meaningful goals with specific deadlines. This will help you plan your further steps and evaluate the results.
- Collect your recipients’ list . Select several ways to gather the email addresses of potential customers. Use lead magnets, banners, pop-ups, ads, etc. Never buy contact information.
- Segment your audience . This will allow you to send relevant offers to specific groups of subscribers based on their needs and preferences.
- Create an appealing email. The sender’s name should be associated with the brand. The subject and preheader should always provoke interest. The body copy should be as informative as possible and have a straightforward call to action.
- Decide on a frequency . Examine your audience and run an A/B test to better understand the best mailing frequency and schedule. This can help you improve email performance.
- Automate emails. This will save time and resources.
- Assess the effectiveness . Constantly monitor the deliverability, open rate, CTR, bounce rate, and conversion rate of your emails. This will help you evaluate your success and plan the next steps to improve performance and conversions.
With these tips in mind, you are ready to launch your email campaign and achieve great results. Good luck!
Hello.This post was extremely interesting, particularly because I was looking for thoughts on this topic last Thursday.
Nice article about email marketing and very useful, thanks for sharing the valuable post.
Thanks! Glad you’ve enjoyed it!
Loved the segmentation part! No one likes irrelevant emails, so I always try to add at least some level of personalization to every email.
Thanks, Jacqueline! You are absolutely right—that’s the way to go!
Thanks for the tips and guidelines!
Many thanks, Maya! Glad you’ve enjoyed it!
Great article. However I still think that emails are more effective when I talk with the customer directly, so I try to avoid the auto-responses.
Hi, Dan! Thanks for your comment. Sure, it is important to add a personal touch and demonstrate attention to customers. But if your email list has over 100 subscribers, you may have a hard time trying to communicate with each one directly. So we recommend automated responses for large businesses that use bulk emails.