An email blacklist is a database that uses real time data that receiving servers can query in order to determine the reputation of the IP address sending the email, or more simply put an email blacklist determines if an incoming message is likely spam.
There are both public and private email blacklists. Public blacklists are, as the name implies, available to the public. Private blacklists are unavailable to the public and unable to be queried externally.
Private blacklists tend to be more strict than public blacklists. If you should end up on a private blacklist, it is not easy to determine why you were blacklisted, so it is important to follow these general guidelines when sending emails:
- Include more text than images
- ALWAYS include an unsubscribe link
- Send from an email address associated with an individual, not marketing@ or email@example.com
Learn: ¿What is Email Bounce Rate?
Avoid spam trigger words and phrases in your subject line, some of which include “Free!”, “Urgent,” “You’re a winner!” and monetary symbols like the dollar sign ($).
To further decrease your chances of ending up on an email blacklist, send email marketing only to individuals who have signed up or opted in to receive your messages.