Adam Yates
15 minute read

Improve deliverability with Email Marketing

With over 90% of businesses generating sales through Email Marketing, almost 40% of emails sent are flagged as spam. Improving the inbox delivery rate by only a few percent can have the potential of increasing sales and growth by a significant amount.

There are a number of ways to improve the deliverability of emails, from a seamless and sound setup, right the way through to the email content itself. We’ve listed the best practices, along with useful tools to help improve your campaigns.

Trusted platform/IP address

The IP address used to send the emails can affect the deliverability of your campaigns. A new or blacklisted IP address won’t be trusted by mail platforms.

If you send less than 100,000 emails per month, it is best practice to use a bulk email service provider such as Mailchimp, ActiveCampaign or Sendinblue. These IP address used to send emails will be shared amongst other users sending emails and using their service. These service providers rely heavily on their IP addresses being trusted and not included in blacklists. Some lesser known service providers may not hold the same level of protection against their IP reputation, allowing their customers to spam against the same IP you are sharing. It’s best to go with a well established, trustworthy service provider.

If you’re sending more than 100,000 emails per month and if your data is strong, you could benefit from sending emails with your own dedicated IP address. Any new IP address will need to be ‘warmed up’, which is a practice carried by slowly increasing the send quantity (starting with 100 a day, increasing until you’re sending to 100,000+). Once trust has been built, your IP will likely outperform any other shared IP address in terms of deliverability.

There are a number of providers who you can purchase an IP address off. FullSphere typically use Mailgun because their API works great. A dedicated email marketing software, such as MailWizz, works amazing for scheduling campaigns and managing data

If you have a dedicated IP address setup, you can use this service, to check whether your IP is blacklisted.

DNS configuration (DKIM, SPF & DMARC)

It is crucial that DKIM, SPF and DMARC records are added to your DNS and setup correctly. Without these records, mail platforms won’t be able to tell whether you (the owner of the domain name) sent the email, or whether the email is being spoofed by someone else. Essentially this increases the security of your emails to improve deliverability.

DKIM (Domain Keys Identified Mail)

A DKIM record is a digital authentication key. The setup is taken from your service provider (such as Mailchimp), or from your dedicated IP provider (such as Mailgun). The full DKIM record should be added to the DNS, exactly as instructed. For a reference, the format will look similar to the below:

Name Type Content TTL TXT v=DKIM1; p=76E629F05F70

SPF (Sender Policy Framework)

An SPF record lists all the IP’s that authorised to send emails. It’s important to include all IP addresses that are being used to send your emails (Email provider, website IP for forms, etc). Here is an example of the setup:

Name Type Content TTL TXT v=spf1 mx ip4: ~all 3600

In the example above:

IP4: is our dedicated IP address which we’re sending emails from

include: contains the record for our Gmail emails and our Mailgun setup

~all tells receiving mail platforms to accept messages from senders that aren’t in your SPF record, but mark them as suspicious (send to spam)

If you’d like to tighten up your security further, you can use –all.

For a more in-depth understand of configuration on the on SPF records, I’d recommend taking a look at this article created by Google:

DMARC (Domain Message Authentication Reporting & Conformance)

A DMARC record essentially ties the DKIM and SPF above together and keeps you in the loop with reports which are emailed to you.

You can use the example below, (remember to update the email address):

Name Type Content TTL
_dmarc TXT v=DMARC1; p=none; rua=mailto:[email protected] 6000

Content: v=DMARC1; p=none; rua=mailto:[email protected]

In the example above, you can change p=none; to p=quarantine; or p=reject;

  • p=none; is used to collect feedback and gain visibility into email streams without impacting existing flows. It’s a crucial first step to setting up the configuration.
  • p=quarantine; allows email receivers to treat email that fails the DMARC check as suspicious and files them in a SPAM folder.
  • p=reject; requests that email receivers reject email that fails the DMARC check.

Error checking the config

It’s best practice to test your emails after the setup, is a great tool which will inform you whether the records have been setup correctly.

Email content

Email content also plays a really big part in deliverability and spam. The content refers to both the subject and body content of the email. There are a number of things we can look at to make improvements:


Sending as a user will always generate a much better response rate than a blanket email, spam filters like it too. You can get very targeted, including first names, and a signature to dress up the email as it would look sending from your own email account.

Avoid spammy words

Keywords such as Free, Investment, Offer and Discount are words which are often picked up by spam filters, avoid these as much as possible. It’s also best to limit exclamation marks! and CAPITAL LETTERS.

Links, images and spelling

Spam filters need to understand your intent. Avoid URL shorteners, check for broken links, and check spelling.

You’ll also want a good text to image ratio. The most common guideline is no more than 40% image coverage and a minimum of 60% text. While exceptions exist, this rule will generally keep you from any deliverability issues.


Because viruses and other malicious software can be embedded into documents, spam filters tend to be very aggressive with attachments, whether it be ZIP, DOCX or PDF. You’ll have much better success rate by removing all attachments and instead linking the user to a landing page.

Unsubscribe links

Hiding your unsubscribe link, or making the process difficult, will only result in poor deliverability. You’ll also encurrage users to hit the ‘spam’ button, which will effect your future sends.

Make the opt out link very obvious and consider adding ‘list-unsubscribe‘ to your mail headers.

Benchmark for open rates & click rates

If you’re wondering how your campaigns are performing, below is a rough guide for open rates and click rates on B2B, UK data:

Score Open rate Click rate
Very Poor 15% 1%
Average 20% 2%
Good 32% 4.5%
Excellent 40%+ 7%+

For more information regarding Email Marketing and anti-spam techniques, get in touch.