Here is a number 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 Score assigns a number to every outgoing mail server. The score is calculated by using 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.

The sender score is on a scale from 0-100, 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. These are called Complaint Feedback Loops or FBLs.

Yahoo, AOL, and Microsoft make it easy to get this information. Gmail allows users to set a Feedback Loop header that does not use the traditional ARF format of most FBLs.

Only ESPs (email service providers) are allowed entry into Gmail’s FBL program.

6. Stick to a consistent send schedule.

One cause for a 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 pre-checked 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 two or three 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 asking 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.

High hard bounce (invalid) rates are the fastest way to trigger filtering and blocking on your 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 thoroughly 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 OK.)

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.

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.

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.

We’ve sent over 60 million emails during 2020. 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 — but only if you get those emails delivered.