Question about spamassassin using MySQL
Paul Lussier
p.lussier at comcast.net
Wed Jan 18 13:59:00 EST 2006
(I'm finally getting to a bunch of interesting threads which I lacked
time for when they were current :)
Bruce Dawson <jbd at codemeta.com> writes:
> Hmmm. So milters actually won't be much good for reducing the amount of
> bandwidth occupied by spam - most of the message comes through before a
> decision is made.
>
> My observation has been that some spammers don't wait for the 250 reply,
> and will just cut the connection after sending the "dot" command.
I'm not sure about sendmail, but I know Postfix has a bunch of
"connection restrictions" it can apply to the incoming connection and
just drop it if whatever criteria you've selected aren't met.
For example:
* reject_non_fqdn_recipient
* reject_non_fqdn_sender
* reject_unknown_sender_domain
* check_recipient_access
* reject_unknown_recipient_domain
* reject_unauth_destination
* reject_multi_recipient_bounce
* reject_non_fqdn_hostname
* reject_invalid_hostname
* check_helo_access
* check_sender_mx_access
* check_sender_access
* reject_unverified_sender
Additionally, you can do things like verify valid senders and
recipients by requirning the sender to:
* conform to the SMTP RFC
* Have a valid hostname
* Provide proper SMTP helo/ehlo statements
* Provide an FQDN in the SMTP helo/ehlo statements
* Provide an FQDN for the envelope sender
* Have no invalid characters in the hostname
* Have a valid destination domain (i.e. no open relaying)
* Provide a valid recipient domain
* Provide a valid recipient user name
* Have a valid nameserver record
* Have a non-empty envelope sender if there are multiple recipients
* Be from a a valid sender address (possibly selective verification)
There are more restrictions you can place on a connection as well, but
these are the main ones. Assuming you required all these
restrictions, violation of any one of them would result in a
dropped/terminated connection.
--
Seeya,
Paul
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