Re: [fetchmail-devel] [Bug #15103] Fetchmail Fails with ASSP (http://assp.sourceforge.net/)

[Frederic M. <fre...@wo...>]

ad...@be... a écrit :
> Bug #15103, was updated on 2009-Jan-23 07:36
> Here is a current snapshot of the bug.
>
> Project: Community Fetchmail
> Category: None
> Status: Open
> Resolution: None
> Bug Group: None
> Priority: 5
> Submitted by: darthasp
> Assigned to : none
> Summary: Fetchmail Fails with ASSP (http://assp.sourceforge.net/)
>
> Details: Hi There,
>
> I am trying to download messages from a catchall mailbox and forward them on to a mail server that sits been an ASSP installation.
>
> The problem I am having is that ASSP only looks at the first 2000 bytes of the message in order to determine whether it is SPAM or not.
>
> If the message that Fetchmail is sending is larger than this size and ASSP considers it to be SPAM - ASSP closes the connection with a 550: response before Fetchmail has finished copying the mail.
>
> Fetchmail then errors with Query status=6 (IOERR)
>
> It does not delete the message or mark it as seen.
>
> next time fetchmail logs in try's to send the message again with the same result.
>
> I can increase the amount of bytes that ASSP looks at and while this solves the issue temporary it is not a permanent solution.  ASSP was not designed to look that the whole message.
> When I increase the amount of bytes ASSP looks at the system resources go through the roof.
>
> Is it possible that Fetchmail could somehow recognise the 550 response from ASSP half way through message sending.
>
> I have enclosed log file for you to look at
>
> Hope you can help 
>
> Regards
>
> Phil 
>
> fetchmail: SMTP> MAIL FROM:<externaluser> SIZE=861742
> fetchmail: SMTP< 250 2.1.0 externaluser....Sender OK
> fetchmail: SMTP> RCPT TO:<internaluser>
> fetchmail: SMTP< 250 2.1.5 internaluser
> fetchmail: SMTP> DATA
> fetchmail: SMTP< 354 Start mail input; end with <CRLF>.<CRLF>
> fetchmail: error writing message text
> fetchmail: POP3> QUIT
> fetchmail: POP3< O07etM6Coi+kFL/DyxZouBPCFDIAEiwZWHF6pjPuZt2vAR+/F0pCL8Re3Qva/m6kfYL7EsD+Vd52
> fetchmail: MDA error while fetching from shrelay@do...@ma...main
> fetchmail: 6.3.9 querying server1 (protocol POP3) at Fri Jan 23 07:26:46 2009: poll completed
> fetchmail: Query status=6 (IOERR)
> fetchmail: normal termination, status 6
> fetchmail: 1 message for shrelay@domain at mail.domain (861742 octets).
> fetchmail: reading message shrelay@do...@ma...main:1 of 1 (861742 octets) (log message incomplete)fetchmail: error writing message text
> fetchmail: MDA error while fetching from shrelay@do...@ma...main
> fetchmail: Query status=6 (IOERR)
>   

I solved this issue by running ASSP in test mode (check option "Bayesian 
Test Mode") and prefixing the subject with something like [SPAM] (in 
option "Prepend Spam Subject"). It means ASSP won't stop mails seen as 
bayesian spam but will tag the subject. The mails can then be filtered 
out automatically by the final recipient.

Since you are downloading your mails with fetchmail, you can't simply 
reject them because it is too late to do that. The purpose in rejecting 
them is to leave the bad mails on the hand of the one that accepted them 
in the first place. But in your case, you already have accepted them and 
you have to deal with them...

If your server is also accepting external mails through direct 
connections via port 25 and you want ASSP to reject those mails, then 
you have to open some kind of backdoor on your mail server to let 
fetchmail inject the mails it is reading. Be sure to properly firewall 
that port to prevent anybody but fetchmail to inject mails.

By the way, I don't advise to let ASSP delete or reject blindly bayesian 
spams because, as you noticed, it doesn't take the whole mail into 
account and, in general, it does a poor job at filtering spams. It tends 
to have a high rate of false positives and you will loose good e-mails 
if you don't keep an eye on what it does.

Frederic