What blocklists are
Blocklists hold IP addresses and domains that spam came from. If you are on one, many receivers reject your mail or sort it into spam.
How it works
Blocklists (also DNSBL, DNS-based blocklist) collect IP addresses and domains that stood out through spam. Many receivers query them for every incoming mail and reject mail from listed senders or sort it into spam.
You usually get listed for one of these reasons:
- A hacked mailbox or website sends spam.
- A contact form can be abused to send to strangers.
- You send to old or bought address lists and hit spam traps.
- The address previously belonged to someone who sent spam.
- Your provider is listed as a whole network because many of its customers stand out.
What matters
- First the cause, then the removal. Otherwise you are listed again right after removal.
- Lists of whole networks hold address ranges or providers. There is little you can do about that yourself; most receivers do not count such entries or only weakly. If delivery problems pile up, changing the sending address or the provider helps.
- Which lists we check: bytereport only queries lists whose terms allow it, for example UCEPROTECT for addresses and URIBL for domains.
How to get off again
- Stop the cause. Change passwords, check website and forms, clean your sending lists.
- Request removal. Every list has its own page for this. Some entries expire by themselves after a few days without a new incident.
- Watch. Check again after a few days.