[Mimedefang] Blocking Dictionary Attacks

David F. Skoll dfs at roaringpenguin.com
Thu Jun 4 17:38:06 EDT 2009

afo cliff wrote:

> I need to have a way to stop dictionary attacks ... unless there is a
> better way I was going to extract the TO address and discard the email
> in mimedefang-filter if the user did not exist when compared against a
> database table of valid users.  I'd be interested to know the
> preferred way to handle this.

[Shameless Plug] Our commercial CanIt software has a dictionary-attack
detector built in that firewalls off hosts that send to too many invalid

We detect valid recipients in a variety of ways (depending on the setup)
including SMTP call-forwards, LDAP, etc.



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