E-mail rejection based on a real-time block list (RBL)

This article describes which real-time blocklists are used to reject incoming emails in the SMTP dialog.

If you have been informed by a sender that it was not possible to deliver an email to you, the sender's email server is configured incorrectly and has been blocked by at least one of the following lists.

Real-Time Blocklists (RBL)

If the sender's mail server is listed on a real-time blocklist, the sender receives the following error message in the SMTP dialog:

550 5.7.1 Service unavailable; client [123.123.123.123] blocked using zen.spamhaus.org; from=bounces@newsletter.top-remise.com, to=john-doe@creoline.de

To ensure future delivery, the sender's mail server must be removed from the real-time blocklist. The following RBLs are used to check incoming emails:

zen.spamhaus.org

The sender's mail server can be removed from the real-time blocklist using the Spamhaus IP and Domain Reputation Checker.

mail.abusix.zone

The sender's mail server can be removed from the real-time blocklist using the Delist function.

mail.bl.blocklist.de

The sender's mail server can be removed from the real-time blocklist using the Delist function.

spam.dnsbl.sorbs.net

The sender's mail server can be removed from the real-time blocklist using a Removal Request.

admin.uribl.com

The sender's mail server can be removed from the real-time blocklist via a Removal Request.

Support

Please contact the respective operator of the real-time blocklist to request unblocking.