Blacklist

Explicitly block unwanted senders and IP addresses.

What a blacklist is

A blacklist (blocklist) lets you block specific senders at the SMTP level — before the message body is even accepted. Blocked senders get a 550 rejection code.

Adding to the blacklist

Under Rules → Blacklist you can block:

• Email address — a specific sender address
• Domain — all mail from a domain (@spammerdomain.com)
• IP address or subnet — useful for blocking botnets

RBL blocking

MXGuard automatically checks the sender's IP against public reputation lists (RBL/DNSBL): Spamhaus, SORBS, URIBL, and others. Servers with a poor reputation are blocked without any admin action.

Unblocking

To lift a block, remove the entry from the list. There's no automatic expiry — entries stay in effect until explicitly removed.