Tips & Tricks For Better Email Deliverability

Everything you didn’t know about email marketing, and achieving the best possible delivery rates!

13 Andrew Willis

Sending marketing emails is easy, right? You just create your fancy content, select who you want to receive it, hit send, the emails magically turn up in your customers inboxes & the conversions roll in.

If only that was the case all the time!

Getting emails delivered into your customers inboxes can be one of the most frustrating things to get right because pretty much everyone has a spam filter of some sort protecting their inboxes and, thanks to the vast amount of spam sent daily (I’m looking at you, dubious foreign lottery officials wanting me to transfer money to release funds & people pushing magic pills), they’re getting less & less lenient with what is allowed through. If your email is lucky enough to make it through, most of the time it ends up in the junk or spam folders and may never be seen.

So how can we increase our chances of making it into the inbox? Thankfully there are a variety of tools available to us which can help, which we’ll take a quick look at below. It’s important to do all of these things though as they all help contribute to making your email look legitimate & being opened.

Sender Policy Framework (SPF)

SPF is a simple email validation system where the IP address used to send an email is checked against a published list of authorised sending IPs.

To perform this check, the domain used in the “From” address is used to obtain the authorised IP list, which should be published in the domain’s Domain Name Server (DNS) records as TXT and/ or SPF type records.

If the sending IP of the email address matches one of the listed IPs then the SPF check is passed.


DomainKeys Identified Mail (DKIM)

With DKIM, a digital signature for an email is generated using a private key & sent as part of the email which a receiving server can then use for authentication purposes. To authenticate the message, a public key published in a domain’s DNS as a TXT record is used to decrypt the signature as well as generate a signature for the email. If these two values match then the email is DKIM valid.

See for more information on this.

Use Reverse DNS

Normal DNS records point hostnames to IP addresses whereas reverse DNS records point IP addresses to hostnames. Some mail servers will do a reverse DNS look up on the IP address that an email was sent from & then check that the hostname then points back to that IP address. If these don’t match up then the check is considered a fail.

IP Warming

The IP address that you send an email from will generally have a reputation associated with it for the quality of mail that it sends & IP addresses with bad reputations are highly likely to not have their emails delivered.

New IPs, or ones that haven’t sent mail in a long time, will not have a reputation yet & mail servers will be wary of letting too much mail through from them.

The idea behind IP warming is to start sending small amounts of mail & then gradually increase the amount so that mail servers can get used to the IP and you can build up the reputation.

Process Bounce Backs & Spam Complaints

If an email cannot be delivered to a recipient for whatever reason, e.g. the customer typed their email in wrong so it doesn’t exist or they’ve exceeded their size quota, you will generally get a response from the mail server responsible for that domain telling you so.

These responses, or bounces, are emails sent back to the address specified in the “Reply-To” field. You may also get them when a server cannot deliver the email straight away but will try again later.

If the bounces you get indicate that an email doesn’t exist, or consistently cannot accept mail, then you should stop sending to that address. If you don’t then your reputation will suffer.

The same goes for spam complaints; if you keep sending to someone who has complained then your reputation will suffer.

You can opt-in to receiving email notifications when a user clicks Junk/ Spam on an email by registering with Feedback Loop (FBL) of an email provider. This notification should contain the email address that generated the complaint so that you can remove them from your list.

Stop Sending To People Who Have Unsubscribed

People who have tried to unsubscribe but still continue to receive messages are highly likely to mark your emails as spam. There may also be legislation or regulatory rules in place depending on the industry you’re in that you may be violating by not removing these people from your mailing list.

Check Your Email Lists Regularly

Over time people stop using email accounts & move on to others. The accounts that are left behind will inevitably be closed down or be unable to accept more mail for other reasons. By checking your lists regularly you can remove these emails from your list & prevent it impacting negatively upon your reputation.

Send HTML And Plain Text Versions

Why do you need to send out a plain text version of your snazzy, newly designed, HTML email? There are two reasons for this.

The first is that some of your customers may open your email on a device that can’t render HTML so they would appreciate a version that they can read.

The second is that sending both versions has a positive impact upon the spam rating of an email so it makes sense to include it even if most people will never see it.

Make Emails Responsive

Ok, this technically isn’t something that impacts upon your delivery rates but it’s good for your customers. Every year the percentage of people accessing web sites & reading emails on a mobile device rises so if your email is only tailored for those people reading them on desktops then you’re alienating a large majority of it’s recipients.


Hopefully this brief post will help show just how much work needs to go into email delivery.

Thankfully, most mail sending tools & services will help along the way with most of these & even do them for you in some instances.

Click here to find out more about Gravytrain and our services or call our solutions team 020 3627 1970.