The 5 Key Factors for Email Deliverability

Email Deliverability is boring.

Yep, we said it, it’s super boring. It’s the OH&S of the email marketing world. But… without taking it seriously, you could land yourself in serious trouble.

Email marketing when implemented correctly can generate 20-30% of ecommerce store revenue which is a significant portion for the low cost of operations. Step one to achieving this goal is making sure your emails actually hit the inbox of your subscribers.

Generally, you should be aiming for a consistent 20%+ open rate for all of your email campaigns and automations. If you’re falling underneath this benchmark even trying different subject lines, then deliverability issues could be bottlenecking your ability to reach your subscribers.

Here are five key factors that email service providers use to determine if your emails should be delivered or not.

IP Address Reputation

When you send an email to your subscribers, it originates from a server’s IP address. Most ESP’s allows many different businesses using their service to send from the same IP address as there are additional costs and technical configuration involved in setting up a unique IP address for every customer.
Occasionally you will have people who misuse the email marketing service and will have their emails marked as spam which can affect the IP address’s reputation with ESP’s like Google and Microsoft. This will affect your ability to land in the inbox of your subscribers.
To combat this, it is always good to use a reputable ESP for your emails that have a strict policy on email spam to ensure those rogue accounts get blocked internally as soon as possible to protect your sending IP.

Domain Reputation

Similarly to the IP Address reputation, the sending domain also has a reputation it needs to maintain. If you are brand new to sending emails from a domain, it would be best to do so in small segments and encourage engagement and interactions with the emails. This will help ESP’s see that people are happily engaging and with new domain which will give it a great kickstart. Some businesses even use a subdomain instead of their main domain for marketing emails. This is so that if there is some negative effect on the marketing subdomain, transactional emails sent from the main domain are unaffected as ESP’s recognise subdomains as a different entity.

Lemlist has a great article walking you through how to warm up a brand new email account:

Spam Traps

To avoid people sharing old email lists that they didn’t get explicit permission to contact, ESP’s often setup spam traps using expired email boxes. Any emails received by these email boxes after a time period after the account has been closed will recognise incoming emails as spam and will affect deliverability on the entire ESP from that domain and IP address. To combat this, it is important to only continue to send emails to “engages” subscribers. Usually, this is around a 3-4 month period before you start removing unengaged subscribers from your list completely.


Specific keywords and synonymous with spammers and can send you instantly to the junk box. Over the years, this is usually to do with heavy sales language like “make profit”, “cash” and “make money”. There are hundreds of these “spam” related phrases that will get your emails in hot water.

It’s best to always run your emails through a spam checker to see if any of your copy gets flagged. Some ESP’s even have a level of spam filtering built-in which gives you feedback as you are writing your emails. But, it’s always best to check with a tool like to be sure.

Don’t Spam

Seems pretty obvious right? Well, some people don’t really understand what is classified as spam.

Spam really is just emails that people don’t want to receive. Whether they had opted in to receiving them or not, emails can be considered and marked as spam by anyone. This is why it is important to have an email strategy and understand the value of every single email that is sent out.

Campaign Monitor’s report show us that a 0.1% unsubscribe rate is the norm. Anything more than that and it should be something to take action on. Ensure people are receiving what they are expecting to from your opt-in’s copy and set expectations.

Spam complaints can also be received from ESP’s and often do. This isn’t an issue as long as your spam complaint ratio is less than 1/1000 emails. This will keep you in the green for ESPs. Any higher, and things are going to go south really fast.

If you do happen to have deliverability issues, there are some actions that you can take to repair the reputation of your domain if you act quickly on it in the right way.


Josh Oastler

Founder and chief strategist at Nifto Digital. Having spent years working in different small businesses and marketing agencies, Josh’s insights are from real-world experience.

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