Email Deliverability 101: Blacklists

We’ve all heard horror stories of domains being blacklisted, but unless it’s happened to yours, you might not understand what it means, or be totally clued-up on how to stop it from happening to you. Chances are you may have asked about blacklists and been chucked a torrent of technical jargon.

Let us break it down for you: there are two types of blacklists, temporary and permanent.


Blacklist duration: hours/days

A typical reason for these types of blacklists: a large number of emails deemed suspicious are sent from the same sending domain in a short period of time.


Blacklist duration: forever

A typical reason for permanent blacklisting: consistently sending emails that are regarded as spam based on feedback loop complaints, and other reasons relating to frequency, quantity, and quality of data.

What to do if you get blacklisted…

Unfortunately, as CommuniGator are not the designated sender, we can’t get you “un-blacklisted,” but we can help with the process. If you have been blacklisted or are having problems with delivery of your campaigns, please contact support for advice.

How to avoid getting blacklisted?

  1. Where possible, send to opted-in (or better yet, double opted-in) email addresses.
  2. Avoid using attachments.
  3. Include an unsubscribe option.
  4. Avoid using obviously spammy words e.g. ‘free’, ‘opportunity’, ‘win’. There is a lot of debate regarding how much specific words affect email deliverability. The research website Econsultancy has produced a useful (and scientifically based) blog regarding the use of words in emails. 45 Words to Avoid in Email Marketing Subject Lines.
  5. Include a view in browser link.
  6. Send to smaller audiences more frequently. Sending one email to a large audience will appear more like spam behaviour than sending to smaller audiences, ideally with varied subject lines and content.
  7. Make your sender email address a person, not a department. Sales@, info@ etc will only increase the chances of being considered spam.
  8. Try to adopt a policy of removing contacts from your audiences who have never engaged with emails. Some email providers will use mailboxes that have become dormant to identify email senders who are using old lists and will consider them spam.
  9. Ask subscribers to add your sending address to their contact list. This will ‘whitelist’ that address for delivery.
  10. Try to reduce the number of images and complexities to an email – the less it looks like a personal email that might be sent between 2 people, the more likely it is to look like spam.

Remember; spam filters are automated systems. No one is reading the email and determining it to be spam; it can take multiple factors to be seen as such. However, once a sender has been judged to be sending spam, it can take time to recover a sending reputation.

And no, it is not advised to simply try to create a new sender as the systems are cleverer than that. For example, the continued inclusion of a website within an email can trigger the identification of 2 seemingly different senders as being the same organisation.

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