Newsletter2Go's had a new name since 14 April 2020: Sendinblue. Learn more   Log into Newsletter2Go
July 25, 2018

How to Optimize Your Email List Building for Engagement and Conversions

Reading time about 14 min
Notebook and pencil against pink background

Email is universally used and a direct line to your audience that not only drives sales but is also more popular than social media and beats every other platform for conversion rate. But, none of that matters if you have a quality email list to receive your emails!

This article will show you how to build an effective email contact list that will give you a high-impact, low-cost means of delivering marketing messages to nurture prospective clients, while also building better relationships with current customers.

Build my next email list with Sendinblue >>

What are the most common types of email lists?

Generally, there are 4 types of email contact lists that marketers use to send promotional emails.


An opt-in email contact list is a directory of email addresses that you have acquired from individuals and corporations who have voluntarily given you their contact details by subscribing through an opt-in form or checkbox during the checkout process. These are customers who have explicitly signed up to receive emails from you.

There are a few different types of opt-in systems that you can use to build your list, including:

  • Simple opt-in: A user signs up by affirmatively providing their contact information by checking a box or typing their information in an opt-in form.
  • Double opt-in: The same as a simple opt-in, except that a double opt-in system sends contacts a confirmation email that they must click on in order to be subscribed.
  • Passive opt-in: The option of subscribing is selected by default and it’s up to the user to unselect this option if they don’t wish to receive emails.

At Sendinblue, we require that all contacts receiving emails from our platform have affirmatively opted in. But, this is also just a general best practice for email marketing. After all, sending emails to contacts that don’t know won’t produce any meaningful engagement, and it can actually hurt your brand and email deliverability. More on that later!


These are sometimes referred to as negative consent or opt-out, in which an individual is automatically signed up to receive your emails after submitting their contact information for an unrelated reason without being informed. For example, a contact may give their email address to receive an order confirmation for a purchase they made on a website. If this website then uses this contact information to send normal email marketing campaigns, this would be an opt-out contact.

Businesses using this strategy leave it up to the recipients to “opt-out” after receiving the emails, typically by including a standard unsubscribe link. This is an easy, non-opt-in tactic of quickly building an email list. It is technically allowed in some countries, but in many cases, it’s against the law (e.g. this tactic is against the GDPR for B2C businesses using personal email addresses).


Here you work with an email contact list provider or data brokerage firm to find and purchase a directory of names and email addresses based on demographics or known interests.

Many times, purchased lists are used for targeting competitors’ customers or a specific demographic/group. It is not the best way of building an email contact list as they are non-opt-in (will talk about it later), meaning they haven’t told you that they want to hear from you.


A rented list is similar to a purchased list because they’re usually acquired through a list provider, data brokerage firm, or other third parties. But your access to a rented list is either single-use or temporary; you do not own the list. That means you usually just provide the content of your email campaign directly to the list provider and they send it for you, since you don’t have access to the actual contact information of the people in the list. This is a non-opt-in style that I strongly discourage.

Why non-opt-in email lists are a bad idea

Contacts aren’t genuinely interested in your product

I referenced this idea earlier hence the need to delve into more details on the matter. The contacts on a purchased or rented list don’t know who you are and likely aren’t genuinely interested in your product/offering. This makes the whole exercise of sending an email campaign result in low engagement.

Many of these rented and purchased email lists are actually scraped from other websites, which is a very low-quality tactic for acquiring emails.

Even if the contacts are opt-in, they opted in to receive emails from the list purchasing company or whoever sold the list to that organization, not your company. The recipient of your emails may not have even heard about your company, which means they have interest in your company’s emails, often leading them to have a very negative perception of your brand and to mark you as spam.

Low engagement leads to bad deliverability

As I mentioned earlier, non-opt-in contacts can be bad for your deliverability.

Most email providers will blacklist your messages if you receive low engagement or a high number of spam complaints. This is not good for email marketing because you can’t see any of the benefits that come with email marketing if you emails end up in the spam folder before they’re even seen by your recipients.

That’s why it’s better to send emails only to contacts who truly have an interest in the content that you’re sending.

18 tips for sustainably growing an email contact list

1. Know your audience

Knowing whom you want to target is essential because the success of email marketing depends on your ability to send content that is relevant and engaging for your audience.

To achieve this, you need to understand the needs and interests of your contacts so that you can create the right content. As you send more relevant content, you can build trust with your subscribers and become an authority and resource in your domain.

2. Have an email strategy

The details of email marketing can easily get you caught up. There are many things to keep track of, such as maintaining deliverability best practices, creating targeted segments and engaging designs, and scheduling your email campaigns for the right time.

You need a strategy that acts as a framework to guide all of these things. Think about the complete life cycle of the subscriber and treat segments according to their specific needs. This will help you build your list in a more purposeful way.

3. Gather the correct data from the start

Your content has to provide value and be relevant to your subscribers. When developing the ideal content for growing your email list, it is important to note that:

  • Quality data is important for knowing your subscribers
  • You can collect this data up front during the signup process
  • You should only collect the essential information — don’t overcomplicate your signup forms

4. Use sign up forms strategically

Sign up forms are one of the most important barriers to address for gathering new subscribers. so you need to get it right if you want to grow your business. Create the form and ask for information later.

The form should be easy to fill out and should appear in multiple places on your website. The more opportunities that visitors have to sign up for your emails, the more contacts you will have in the end. Just remember to avoid the common mistakes that many businesses make with opt-in forms.

5. Implement a double opt-in system

I mentioned this system earlier, but I didn’t go into detail. Double opt-in is one of the best tactics that you can use to build a high-quality, engaged list of contacts for your business.

Because contacts must confirm their subscription before they’re added to your list, you can be sure that you’re only sending emails to the most interested and engaged contacts. Another advantage is that you will know the email is valid and monitored, which reduces your hard bounce rate from fake or misspelled email addresses.

6. Create a compelling reason for users to opt-in

Generate more signups with a strong call to action that offers new subscribers a resource or promotional discounts. These offers increase the incentive for visitors to sign up for your emails by creating an exchange of value, rather than just asking for contact information straight up.

But, it’s important that the opt-in incentive be highly relevant to the target audience or it won’t have a strong effect on your subscription rate. You need to factor in the desires and needs of your potential customers so you can craft the most compelling incentives for encouraging more signups. Examples include email templates, online courses, checklists, cheat sheets, resource lists, and eBooks/guides/reports.

7. Use gated content strategically

Generate a free resource or online tool that can act as a lead magnet for collecting email addresses before being downloaded.

Users want value, so providing them with in-depth resources and tools like eBooks and infographics are very successful at bringing in more signups. Whenever users find the resources valuable and helpful, they develop more loyalty for your brand.

8. Provide subscribers with valuable content

Killer content makes subscribers come back. It’s as simple as that. If you are addressing real problems that your subscribers face in their lives with your content, they’re going to sign up.

So, whenever you create a new article or eBook, make sure that you ask yourself, “what problem am I solving for my customers?” If you can’t answer this question, you might want to rethink your article and create something with more focus on the needs of your audience.

9. Create a strong opt-in CTA

A strong call to action convinces a person to get over the pain of giving out their personal contact information and inviting you to send more emails to their inbox.

The copy of your opt-in CTA needs to be on-point with a clear value proposition if you want to attain a higher conversion rate. Buttons that just say “subscribe” aren’t very galvanizing for users, so convince them that they’re missing out if they don’t give their email and sign up for your list.

To craft the right CTA, just ask yourself: “what is the direct benefit that a user will gain from subscribing?”

10. Give customers multiple opportunities to subscribe

There are many different types of opt-ins that you can implement on your website. Whether you end up using static opt-in forms or more dynamic popups and slide-ins, you want to make sure that you give users as many chances as possible to sign up without being overly distracting or diminishing the user experience on your site.

For example, you can use static forms in your sidebar and/or website footer, then implement popups or slide-ins on specific content pages that have more targeted CTAs related to the content on the page (e.g. “Want to know more about marketing automation? Sign up for our eBook now). This creates multiple opportunities for users to sign up for your email list while also allowing you to diversify your value proposition and CTA.

11. Create user-friendly subscriber forms

The opt-in form should allow for easy subscription to receive emails and communicate any relevant information that helps you know more about what they’re looking for from you. Do this by adding extra form fields to get information you can use for email segmentation (e.g. date of birth, geographic location, company info, etc.).

Although it’s a good idea to collect some segmentation data from new subscribers when they sign up, you should still make sure that the signup process is as simple. Otherwise, users will be deterred from signing up because it’s too much work or you’re asking for too much personal information.

12. Collect subscribers at checkout

If you have an eCommerce store, you should use the checkout process as another place to gather subscribers for your email list. Add a “join our email list” checkbox below the email field on the checkout page so that new customers can easily sign up at a time when they’re most interested in your business.

Allowing customers to sign up for your email contact list in this way is great because you’re adding contacts who have a proven interest in your business. This enables you to encourage repeat purchases and increase customer loyalty by sending a professional-looking newsletter or other targeted email campaigns.

13. Measure email list metrics to test emails and content to see what works

Identify the source of your traffic that delivers the most subscribers and the highest conversion rates. All you have to do is set up goal tracking in Google Analytics and look at your subscriptions by channel.

Once you know this information, you can learn how you can continue to grow your list by optimizing your content strategy and focusing efforts to bring in more traffic from high-conversion channels.

14. Clean your email list regularly

Keeping a clean email list is very important if you want to keep engagement rates with your emails high. This means doing away with disengaged or old contacts.

Growing a big list is important, but you can’t sacrifice quality to achieve quantity. Having a massive email list full of people who don’t open your emails and act on your offers doesn’t help your business at all. Instead, periodically clean your email list so that you only have people who are interested in what you have to say.

15. Create an email preference center

This is an influential tool that gives your users the option to remain on specific lists and unsubscribe from others rather than just a blanket unsubscribe. This helps you keep marketable leads in the mix while giving your subscribers a better experience. You can let users define preferences based on:

  • Content interest
  • Email frequency
  • Types of offers

Preference centers give your subscribers the option of managing the types of emails they receive from you, increasing overall engagement and ultimately, conversions.

In Sendinblue, you can do this with the help of our multi-list subscription forms. Learn more in our help center article on the topic.

16. Ask disengaged contacts to re-opt-in

Although I mentioned that you should clean out any old or disengaged contacts from your list, but you can still try one last tactic before you purge them from your list: a re-opt-in campaign.

Before you delete your inactive subscribers, use marketing automation to segment them into a new email list and send them an email asking if they’re still interested in receiving your emails. If they don’t engage within a certain period of time, you can remove them from your contact database.

This is a great tactic because sometimes people get busy — it’s a good idea to give subscribers the chance to re-opt-in. Plus, you’ve got nothing to lose since they’ll be removed from your list anyway.

17. Build your social media presence

If you have a strong social media presence, you can use this to your advantage to gather more subscribers. Schedule posts to periodically remind your followers and fans that you have a newsletter or email list that they can sign up to get even more exclusive offers.

The key is to treat this just like any other CTA — you need to make the offer interesting enough for the readers to convert. Remind followers of the value that they will get from signing up for your email list. If you offer a “signup bonus,” such as a one-time discount, be sure to highlight that as well.

18. Join trade fairs and events

Offline events like expos and trade fairs are good ways of reaching your target audience. The shows are frequented by highly focused people likely to make up your target market.

Don’t miss out on the chance to collect these contacts just because you’re meeting in person. You can either keep a physical signup sheet — or better yet, have your laptop or tablet ready with your subscription form so people can just type their email address right there.

Final thoughts

If you work on your email list building in the right way, you won’t have any problem generating meaningful engagement from your subscribers.

But, list building is only the first step in building a successful email marketing strategy. From there, you should focus on creating high-quality email campaigns and well-designed newsletters that are optimized for your goals and provide value for your readers. As long as you keep the needs of your contacts in mind, you can’t go wrong!

Don’t have an email marketing account yet? Try Sendinblue today!

Ready to find your marketing zen?

Take the stress out of your work day with a solution that’s built for you!

Get started free