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How to maximize the deliverability of B2C / newsletters / opt-in / transactional emails

In this guide, we give you the best recommendations to help newsletters / B2C / opt-in emails land more often in inbox.

The provider you send your emails from is crucial (50%+ of your deliverability is influenced by it).

The email service providers with the highest deliverability for B2C emails are:


These providers are superior in terms of deliverability because they have great deliverability management systems.

In other words, they're strict with their customers and :
If their customers have a high spam complaint rate, they can kick them out. As spammers decrease the reputation of sending IPs, minimizing the number of spammers is one of the best ways for email service providers to maximize their IP reputation. Typically, MailChimp are super strict and this helps them get superior results.
They have different IP pools based on their customers' sending practices. If your sending practices are premium, you'll be allocated a premium quality sending IP. If your practices are average, you'll be allocated an average quality sending IP, etc.

In short, using one of these providers combined with following the best practices is the definitive way to optimize your deliverability.

The worst providers to land in inbox are custom SMTPs, in-house SMTPs and anything exotic, not reputable to the eyes of the major mailbox providers such as Google and Microsoft.

The more exotic is your email service provider, the more likely you'll land in spam.

That's why the absolute best providers to land in inbox are Google Workspace and Office365 (but they won't work for a newsletter / B2C / opt-in emails sending use case).

Email warming doesn't really work for B2C / Newsletter emails

Most email warmers, including MailReach, are focused on raising your sender reputation with professional inboxes, not personal ones. It's nearly impossible to warm with personal inboxes.

That's why MailReach's warmer won't be a good fit to build your sender reputation with personal inboxes.

You need to maximize your engagement rate

That means:

Remove from your list the recipient who don't or poorly engage with your emails. These recipients drag down your engagement rate and, as a result, your sender reputation.
Make sure to send emails to people who actually opted in.
That's obvious, but send relevant emails and try to solve your recipients's pain as much as you can. If you send boring emails nobody cares about, then your engagement will be low and your sender reputation will be low as well.

Your need to minimize your spam complaints rate.

Since early 2024, if you send more than 5k emails / day, you need to have a spam complaint rate below 0.3%.
Monitor your spam rate with Google Postmaster Tools.

Your content is very important

The fewer links the better for your deliverability.

Use our Email Spam Test to test if your links cause spam.

In a lot of cases, removing links can instantly increase your deliverability.

Some topics can make you land in spam very easily.

Especially in the following industries :

Money earning / growth / saving / investment / stocks / sales / "sell more"
Money games / casino stuff / betting
Loans / mortgage / credit / debts
Real estate
Security / cybersecurity
Health / diet / weight loss
Sexuality (you know, penis enlargement and all that)

If you're in any of these industries, you have to be extra careful of the words you use. Our Email Spam Test is your best friend to test your content and iterate if needed until you find a version that lands in inbox.

Make sure to setup a custom tracking domain

Tracking can put you in spam. By setting up a custom tracking domain, you minimize your risk of spam related to the tracking.

Read this guide:
What's a custom tracking domain and why you absolutely need one.

Make sure to use the List-Unsubscribe header

A list-unsubscribe header is an email header that contains specific instructions about a brand's unsubscribe process that inbox providers—like Gmail, Apple Mail, or Yahoo—can use to power native unsubscribe functionality in their inboxes.

More info about what is the list-unsubscribe and how to set it up in this guide by Brevo.

Make sure your SPF, DKIM and DMARC are well setup.

To test that, you can use:

Our Spam Test
Our SPF Checker
Our DKIM Checker

MailReach's Spam Checker is important to monitor your deliverability

The only way to measure your deliverability and inbox placement is to actually send an email to a list of mailboxes (according to the type of mailboxes your actual recipients use) and check where your email landed.

You CAN'T measure deliverability if you don't send an email. That's why tools like are mostly useless. You can have 10/10 on and still land totally in spam.

Updated on: 14/06/2024

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