Introduction

A DNS Black List is a public domain name server that keeps a list of IP addresses that are black listed for some reason. Most of these lists contain information about mail hosts that are open (i.e. will relay unauthorised mail) and can therefore be abused by spammers and other bulk-mail senders. Other lists are simply known sources of spam. By choosing to verify connecting clients against black lists you are choosing to refuse mail from them based on these criteria.

Blacklist Tab
This tab, accessed from the SMTP Service dialog and the Remote POP3 Mailbox properties dialog, enables the Black Listing facilities to be configured for this instance of the Service.

Explicit Black and White Lists
Click on these buttons to enter lists of client IP addresses, sender e-mail addresses and recipient e-mail addresses to black list or white list (respectively). Clients that send a message which matches the black list, or who are blacklisted by one of the configured DBLs, will be barred from sending any further messages for a period of time.

DBLs
DBL (DNS Black Lists) servers can also be configured, which allows Mailtraq to use public black lists to determine whether or not a client should be allowed to send messages to Mailtraq.

Click here for a tutorial on configuring DBL

Tarpitting
Tarpitting is the term given to a process which combats spam and abusers by making it difficult to send large volumes of mail. If Tarpitting is enabled and a client becomes blacklisted, rather than immediately refuse the connection or refuse the recipients, they are accepted but delayed substantially. This does not add any load to Mailtraq, but prevents the client from delivering additional messages to other servers. After all the recipients have been listed, Mailtraq will still refuse the message.