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12 Ways to Improve Email Deliverability

I rave about email marketing all the time.

But I need to shoot straight with you about email marketing lest you think it’s some holy grail of marketing.

Your emails are useless unless they actually make it to the user’s inbox.

Let me state that another way so you don’t miss it. If your emails aren’t getting delivered, then email marketing is a massive waste of time and money.

You’ve probably read all the tips about subject lines, open rates, engaging content, powerful CTAs, and strategic email landing pages. But let’s take a big step back and look at the picture from its most foundational level — email deliverability.

I’ve collected 12 of the smartest and most effective techniques for improving email deliverability.

1. Prime your IP for success.

The job of ISP filters is to defend against spam emails. How do you tell these filters that your IP is valid and trustworthy?

Start any email campaign by sending small batches of emails. Send these messages to addresses that you know are engaged.

As these emails are received and opened by engaged users, your IP will start to build trust, in a manner of speaking, with the ISP. Slowly increase the number of emails, until you scale to your peak volume.

2. Register a subdomain and use it only for email activity.

I don’t recommend it for everyone, but you may wish to create a subdomain that is exclusively for email marketing purposes. Over time, users will come to trust the subdomain, which is an added benefit.

The real purpose, however is that this subdomain will allow for domain-specific monitoring of your IP reputation, and be able to succeed against some domain-based certification filters.

3. Implement a sender policy framework.

A sender policy framework or SPF increases your trustworthiness in the eyes of the receiving email server. The server can cross check the domain name against the associated IP address to make sure that it is legitimate. If you don’t have an SPF in place, your emails might be rejected.

4. Check your sender reputation.

The biggest reason why your emails are not delivered is due to a low sender score. ISPs automatically reject any emails that fall below a certain score.

Sender Score is produced by Return Path. Sender Scores assigns a number to every outgoing mail server. The score is calculated by using the traditional email metrics such as unsubscribes and spam reports.

Here is a report that I pulled for one IP from which I occasionally receive marketing emails.

sender score metrics

The sender score is on a scale from 1-100; the higher the better. The report above, at a 96, is a good score.

It’s important that you keep a close eye on your score. You can use Sender Score to get this information for free.

5. Check feedback loops.

Most major ISPs provide feedback loops, in which the email sender can gain information from the recipients who have complained about that sender’s email. Complaint Feedback Loops or FBLs.

Yahoo, AOL, and Microsoft makes it easy to get this information. Gmail reported earlier this year that they are testing a new feedback loop, that differs in that it does not use the traditional ARF format of most FBLs.

Only ESPs are allowed entry into Gmail’s FBL program.

6. Stick to a consistent send schedule.

One cause for lower sender score and IP rejection is random and erratic broadcast activity. If you are not maintaining a regular schedule with your emails, it creates sending spikes. Do your best to stick to a consistent email sending schedule.

7. Use a double opt-in or confirmed opt-in.

The most popular form of opt-in is the single opt-in, in which the user agrees to receive an email by simply checking a box, or leaving the prechecked box checked. This might seem like a great strategy to harvest email addresses since it’s so easy and automatic. However, it can backfire by generating high amounts of spam complaints. Spam complaints are dangerous. Some ISPs begin to block sending servers after as few as 2-3 spam reports per one thousand emails.

The best way to defend against spam complaints is to use a double-opt in. All you do is send a confirmation email to the new subscriber in order to validate their address and gain their consent. (In some European countries, double opt-in is now a mandatory requirement.)

8. Purge your list.

If you’re sending your marketing emails to non-existent users, you’ll ramp up your bounce rate and destroy your send credibility. Every now and then, remove all inactive recipients from your list filtering out all users who have not opened or clicked your emails in a few months.

According to Oracle, “high hard bounce (invalid) rates are the fastest way to trigger filtering and blocking on your new IP.” You may want to use a paid service to clean all hard bounces before you launch a fresh email marketing effort.

Additionally, most email validation services can catch duplicates, typos, outdated domains, do-not-email records, bogus addresses, and other common user errors.

You’re not going to lose anything by cutting the dead weight from your list.

9. Filter contest entry email signups.

The worst email lists are created from giveaways or signups. People, true to their nature, will attempt to enter multiple times using invalid or nonexistent email addresses. They don’t care about getting on your email address list; they care about a chance to win a free iPad mini.

If you are using a contest or giveaway as a method of gaining email subscribers, then you need to vet this list hard before dumping it into your subscriber list. It could be a source of hard bounces, which could land you on the IP naughty list.

10. Send emails at just the right frequency. (Once a week is probably okay.)

Too many emails can burn your subscriber list. Too few emails can kill your revenue.

So what do you do to maximize deliverability? You send just the right number of emails. The only way you can find that perfect number is by thoroughly testing, which isn’t easy. Plus, it takes a long time, during which time you might make some mistakes.

A good benchmark is one email per week. You can try scaling up to twice weekly, as long as you have really good content. You can even drop back to once a month without totally losing touch with your audience. But if you go anywhere outside of those two boundaries, you’re in dangerous territory.

11. Use branding in your “from” name.

Using your brand’s name in your “from” line will help to reduce spam complaints. It’s also been proven to improve open rates.

Increasingly, some companies use a front person, an individual, to head up their email marketing in order to give it a more personal feel. You can still use this approach. Just add “from [business name] after the individual’s name.

a branded email

12. Check blacklists.

If you’re experiencing send problems, or even if you’re not, it’s a good idea to check the blacklists. These DNS-based blacklists are created to protect users from IPs that have received a high volume of spam reports.

Make sure that your IP is not on this list.

I did a quick check on an IP using MXToolbox. The report looks good. If I wanted to, I could sign up for a free monitoring service.

IP address blacklist

Conclusion

In order for email marketing to be effective, the emails have to get delivered.

That’s step one. After that, you can go crazy with creating killer subject lines and powerful email content.

Since 2007, I’ve sent over 60 million emails for my blog, Quick Sprout. That’s a lot of emails, and it seems like a lot of risk. But I’ve been able to use my large email list to increase revenue and drive up engagement.

Email marketing works wonders — only if you get those emails delivered.

What insights have you learned about email deliverability?

About the Author: is a lifelong evangelist of Kissmetrics and blogs at Quick Sprout.

  1. Hi Neil,

    So clearly and concisely explained. What’s even better from my own personal point of view is that I can already tick most of the boxes but it’s still nice to have it all confirmed.

    One way I’ve found of making sure you put out something every week (or twice a week in my case) is to enable your autoresponder to use the RSS feed from your blog, so that your subscribers have a reminder that you exist. This is also a little motivation to update your blog on a routine basis!

    Thank you for this nice little batch of tips.

    Regards,

    Steven Lucas

  2. Wow! 60 million emails?! I have some serious catching up to do!

    Excellent deliverability tips anyway – everyone should follow this advice when mailing.

    What are your thoughts of text versus html format emails?

    Personally I prefer simple text format for emails I get but for sending I am in two minds – they are harder to track in text but I suspect they get more views and less likely to be flagged as spam, whereas html format allows for tracking and links look better, as well as of course allowing for a fancy graphical layout with more opportunities for branding and embedding CTA’s.

  3. Thanks for this thorough overview, Neil. It’s spot on!

    Deliverability isn’t a sexy topic, but it’s foundational for a successful email program.

    If you’re looking for a fun, engaging way to learn about email deliverability, check out this Marketing Profs post:

    How Is Reaching the Email Inbox Like Getting on Kanye’s VIP List?
    http://www.marketingprofs.com/articles/2016/30114/how-is-reaching-the-email-inbox-like-getting-on-kanyes-vip-list

  4. What percent difference should adding SPF and DKIM make to deliverability?

    Due to some weird SPF record input style issues with my host I spent a couple hours setting it up and noticed a 0% difference.

  5. My comment on your tip
    “Start any email campaign by sending small batches of emails. Send these messages to addresses that you know are engaged.”
    This is so vague it is for the most part meaningless without some numbers or range of numbers.
    “small batches” is 100 small or 50,000 small?
    Some companies would consider 100 a small batch while larger companies may consider 50,000 a small batch.
    I would suspect that an IP reputation would be affected differently seeing 100 email versus 50,000

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