Dear Marketer,
Hey. It’s me, your email service provider.
You know, the one quietly sending every newsletter, abandoned cart nudge, and product launch email you passionately build.
I’ve seen your campaigns. Your beautiful CTAs and well-timed workflows, too. But can I be honest?
Your email list building habits are…stressing me out. You’re adding contacts who don’t want your emails, forgetting to validate addresses, and growing your list as if it were just a numbers game.
And then you wonder why your open rates drop, your bounce rates spike, or your email deliverability tumbles.
Don’t worry—nobody needs more judgment here. I’m here to make things a little simpler for you.
If you want better inbox placement, fewer deliverability issues, and subscribers to open, click, and maybe gush over your emails, here are 7 list growth strategies I’m begging you to try.
Strategy 1: Please—Just Use Double Opt-In
Smarter list growth is the MANTRA leading email marketing experts emphasize in this Email Mavlers’ infographic—Email Trends & Insights, 2025, and trust me, they’re not just saying it to sound fancy.
And one of the smartest and simplest ways to build a list organically is double opt-ins.
Double opt-in is the difference between building a targeted, high-quality list… and building a mess. With a double opt-in system, subscribers are only added to your list after they confirm their email via a second step, usually a link in their inbox.
Here’s what it does:
- It confirms if the email is valid, without typos.
- It confirms the real owner signed up, not a bot.
- It shows genuine intent, which means better engagement and fewer unsubscribes and spam.
In the words of Nick Schafer, Sr. Manager of Deliverability & Compliance at Sinch Mailgun:
“I would recommend that every sender use a double opt-in all the time. Not only does it ensure you only acquire subscribers who are more likely to engage, but it also helps prevent bots from abusing signup forms, which is a significant email security risk.”
I agree. Using double opt-ins might slow down your subscriber signups. But then, do you really want a bloated list of problematic email addresses? I’d take a smaller but healthy list over thousands of unvalidated emails any day.
Over time, you’ll spend less effort and fewer resources.
TL;DR: With a double-confirmed email list, your emails garner better engagement and fewer complaints. And also puts you out of the deliverability troubles.
Strategy 2: Don’t Just Ask for an Email, Offer Something Worth It
Would you hand over your email address just because someone asked nicely?
No, right?
You have to give people a reason, a compelling one, to join your email list.
This is where your lead magnet does the heavy lifting. It’s offering something valuable in return for their email address.
So what counts as “real value”? Well, it varies with the target audience. But let me give you a few examples of proven performers:
- For B2B brands: Research reports, practical tools, exclusive content, or webinar access. Example: “SaaS Budget Allocation Study” showing how companies prioritize spending.
- For service businesses: Offer practical resources like templates, proven examples, quick reference guides, or client success stories. A marketing agency might create “Email Sequences That Convert” with real examples from their campaigns.
- For creators or media brands: Give subscribers exclusive content like preview episodes, backstage footage, or useful downloads. A podcast host might offer bonus interviews or unedited conversations that didn’t make it into the main show.
Once you’ve got your lead magnet nailed, package it well:
- Create a landing page that paints the value clearly.
- Short signup forms are better. Name, email, and maybe one segmentation question.
- A/B test the headline or offer.
- Explain why they should subscribe beyond the freebie. What kind of emails will they get, how often, and what’s in it for them?
Promote your lead magnet on:
- High-traffic blog posts or ones solving a related pain point
- Your homepage and About page
- Social media bios and content
- Exit-intent or timed pop-ups
Why does this matter for deliverability?
Because when people sign up in exchange for valuable resources, they’re more compelled to engage with your emails. And not mark you as spam.
TL;DR: Offer something worth trading email for, and they’ll treat your emails like something worth opening.
Strategy 3: Validate Emails Before They Enter Your Database
Don’t contaminate your contact list with junk data.
I am referring to the misspelled domain—gnail.com, a fake address, or a disposable email that vanishes in 24 hours that someone entered just to grab your lead magnet and run.
You don’t want those entries as they mess with your metrics and hurt your sender reputation.
Nip it in the bud by setting up real-time email validation at signup. It’ll catch:
- Obvious typos in domains
- Invalid syntax (like extra spaces or missing “@”)
- Disposable or temporary email addresses
- Role-based addresses like info@ or support@ that don’t usually engage
You can use standalone tools like ZeroBounce, BriteVerify, or MailboxValidator to validate new email addresses. Some of my fellow ESPs even bake it in.
And if you’re bringing in older lists or running cold campaigns, you can even run bulk validation before you send emails. Nonetheless, it’s also possible to re-engage the dead email lists.
Strategy 4: Don’t Buy Email Lists, Build Your Own
Purchased email lists are temptingly common that nearly 1 in 10 email senders admit to using them to grow their database.
But beneath that shortcut lies a minefield of deliverability issues, spam complaints, and potential legal trouble. Only waiting to tank your sender reputation, damage your ESP relationship, and blacklist your domain from inboxes.
The purchased list is nothing but users who have never permitted you to send them your emails. They were forced to.
Naturally, they will toss your emails into the spam folder. Enough of those complaints, and your sender reputation declines.
As your ESP, I monitor that closely. Because a poor reputation doesn’t just affect your campaigns, it affects every sender on the platform. That’s why emailing purchased lists is likely to breach our terms of service. Repeat offenders often lose access entirely.
There are legal risks, too. GDPR and CAN-SPAM laws can hit you with penalties for sending emails to people who didn’t ask for them. Plus, Gmail and Yahoo keep making their spam filters stricter. Hence, purchased lists rarely even reach inboxes anymore.
For email marketing that works long-term, you need to grow your list the right way with people who genuinely want to hear from you.
TL;DR: Smart signup forms, useful freebies, and helpful content bring in subscribers who care about your emails. This keeps your list clean and your messages out of spam folders.
Wrapping Up
Growing your email list organically is an industrious task, but a worthwhile trade-off given the better results and fewer headaches.
An email list filled with contacts who have a legitimate interest in your emails benefits both your sender reputation and deliverability.
Subscribers who have given explicit consent to receive your communications are also more likely to engage, and that’s exactly what inbox providers look for. It signals that your messages are wanted, not spam.
On the other hand, uploading contacts who didn’t opt in or using a purchased list sends the wrong signals. Getting ignored, flagged as spam, or blocked shouldn’t come as a surprise.