Your company’s sender reputation, the credibility that Internet Service Providers (ISPs) place on your domain to allow for more efficient junk email filtering, is probably the most important factor determining the success of your email marketing campaigns.

ISPs have been fighting spam mail since the mainstream adoption of email in the 1990s. While their approaches to identifying and blocking spam email have undoubtedly improved in the last 20 years, I think anyone who has an email account would agree that spam email is still a problem. It is estimated that around 70% of all email is spam. The ISPs’ war on spam has inevitably led to lots of organisations sending email being caught in the crossfire.

ReturnPath claims that up to 20% of legitimate email never reaches the inbox. Companies put a lot of effort into devising their email marketing strategies, crafting their messages and call to actions and optimising their landing pages but they could be wasting massive amounts of time and money if their emails are never received by customers. But how do you improve your organisation’s sender reputation?

Maintain a clean list

List hygiene is a key factor determining the deliverability of your emails. To ensure your list is clean, you should adopt a double opt-in process (verified by email) to ensure that your subscribers have not signed up by mistake and that they have provided the correct email addresses.

Furthermore, you should make unsubscribing as easy as possible. Avoid paying for cold email lists – even if they claim to be verified using a double opt-in address.  You may also want to consider using an email validation service if your list is relatively old or you’re unsure about the quality.

Improve sender authentication

Sender authentication is a technique whereby the identity of an email sender is checked to ensure that they are who they claim to be. ISPs use one a combination of authentication methods to verify the sender’s identity.

Sender ID

To prevent spoofing, ISPs verify the sender domain against the IP address of the server from which the email is sent.

DKIM (Domain Keys Identified Mail)

DKIM involves adding a field in the message header which acts as a digital signature which can be validated by recipients.

SPF (Sender Policy Framework)

Further authentication is provided by the Sender Policy Framework whereby messages are validated against an SPF record in the domain’s DNS zone to ensure validity. The easiest way to ensure that you have sender authentication in place is to use a reputable Email Service Provider (ESP). ESPs often have relationships with ISPs and email being sent from an ESP’s server would normally pass the authentication checks of most large ISPs. However, mail sent using ESP’s software doesn’t guarantee deliverability.

Minimise spam complaints

Most ISPs offer the ability for customers to mark an unsolicited email as spam and any organisation can be reported for spamming. A lot of providers make spam reporting really easy. For instance in Gmail, there is a button to report spam in the main toolbar, dangerously close to the ‘archive’ and ‘delete’ buttons. Similar functions exist in Yahoo Mail and Hotmail.

Most companies will eventually receive a spam complaint if they send large enough volumes of email. Luckily ISPs allow for a few spam complaints before taking action. So if your spam complaints are within acceptable levels (thought to be around 0.01%), then you shouldn’t experience issues. Avoiding spam trigger words, ensuring a high text to image ratio and conducting some simple testing before sending your email to your list of subscribers is also highly recommended.

Avoid spam traps

Spam traps are a cunning technique used by ISPs to identify and block spam. Spammers often use bots to harvest email addresses from the internet, so ISPs use this knowledge to catch spammers in the act. They set up traps by publishing email addresses on web pages that are only accessible by bots. If these email addresses subsequently receive email, it is extremely likely that the sender is a spammer as a legitimate sender should not have these email addresses in their mailing list. Sometimes email addresses that haven’t been in use for a while are used as spam traps.

So, maintaining a clean email list and making it easy to unsubscribe will ensure that your organisation doesn’t get caught in a spam trap.

Create engaging content and delight your email recipients

Above all, you should strive to create content that your customers are happy to receive and share. These customers will help you send the right signals to ISPs concerning your email (such as high open rates and emails that have accidentally ended up in junk mail boxes being flagged as ‘not spam’), improve your future deliverability and increase the likelihood of success from your email marketing efforts.