An email blacklist (also known as a DNSBL or RBL) is a real-time database that identifies IP addresses or domains believed to be sources of spam. Internet Service Providers (ISPs) like Gmail and Outlook use these lists to filter incoming emails and protect their users. If you’re on a blacklist, your emails are likely being sent straight to the spam folder—or not being delivered at all.
If too many recipients mark your emails as spam, ISPs take notice. This is the most direct way to damage your reputation and land on a blacklist.
Sending emails to old, invalid, or inactive addresses results in high bounce rates. This signals to ISPs that you aren’t managing your contact list properly.
A sudden, massive increase in the number of emails you send can look suspicious. Warming up your IP address by gradually increasing volume is essential.
If your server or an email account is hacked, it can be used to send spam without your knowledge. This will quickly get your domain or IP blacklisted.
Require new subscribers to confirm their email address. This ensures you have an engaged list and prevents fake sign-ups.
Keep an eye on your bounce rates, complaint rates, and open rates. Address any unusual activity immediately before it becomes a problem.
A clear unsubscribe link is essential. It’s much better to lose a subscriber than to get a spam complaint.
Use strong passwords, set up authentication records like SPF, DKIM, and DMARC, and ensure your servers are secure.