A blacklist is an online database that aggregates email addresses and domains that have been reported on multiple occasions to be sending out spam or malicious content to others on a large scale. These blacklists are used as a reference by mail servers to determine how safe it is to accept messages coming from unknown domains and addresses.

How do email blacklists work?
A blacklist acts as a reference point for other mail servers to determine the history of another domain online. When an unknown email first makes contact with a mail server, determining the authenticity and validity of the sender is difficult to assess due to the amount of unknown information a mail server has available to them with 1 piece of mail. Blacklists exist for the benefit of the internet in general, as they act as a “No Entry” list based upon what negative behavior other mail servers have reported. The primary activities that would land a domain onto a blacklist are as follows.

  • Having a high bounce rate
  • Having a high amount of emails be manually flagged as spam
  • Having a low amount of engagement with your emails.

A general rule of thumb regarding how blacklists work is that if you participate in email activity that can be interpreted as spam, malicious, or unwarranted then it can end up landing you on a blacklist.

How do I find out if I am on an email blacklist?
The easiest way for you to determine if you are on a blacklist is to simply sync an inbox under the domain in question to our platform. Every inbox synced to Warmup Inbox gets run by the 24 most common IPv4 blacklists to determine if your inbox and associated domain has been listed on one.

How do I reduce my risk of getting onto a blacklist?
The best way to avoid getting listed on a blacklist is to engage in proper email practices such as.

  • Verify all email addresses before attempting outreach
  • Avoid sending unnecessary emails
  • Avoid the use of spam words within your email drafts
  • Keep your sending volume to a minimum (30-50 a day if your inbox has been warmed up with us for at least 30 days)

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