Block Cracking! What is it?

We have implemented “Block Cracking” on our email system, taking it one step further to removing spam entirely.

https://github.com/Exim/exim/wiki/BlockCracking

This is called Block Cracking as it is designed to stop people trying to Brute Force their way into your email server, however, we already have that in hand and have only implemented the outgoing Spam Counts.

The principle is not to limit the number of emails sent, but the count number of send emails that bounce back “refused” due to them being non-existent.

So the system counts the number of emails sent by scripts or authenticated users, and if too many non-existent recipient email addresses are sent the scripts or users are blocked from sending further emails.

If the emails are sent by an authenticated user, and that user sends too many non-existent recipient emails (spams) then the emails are blocked for that user until their password is reset by their reseller or administrator.

Administrators, Resellers & Users are emailed when a detection and block happens, often if no contact is made by the reseller or user, an administrator will often follow up with an account suspension until contact is made.

This stops our servers getting blacklisted by spammers, and the reputation of our IPs intact.

This helps to stop spammers and compromised scripts whilst forcing users to fix their issue.

We anticipate quite a few notifications happening in the first couple of months, as we are now able to determine when any spam appears, and who and what sent it.

(So spammers, please don’t host with us, you will not get away with it!)

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