[Mimedefang] Hot do I stop becoming a spam relay.

Jeff Rife mimedefang at nabs.net
Sun Mar 11 12:01:03 EST 2007

On 11 Mar 2007 at 14:35, Andrew Watkins wrote:

> Hi!
> First of all my sendmail does not allow relaying, but I am now getting a 
> lot of e-mail where email is sent to an unknown local user and then 
> there is a BCC to some other location:
> for example:
>     From: spammer at domain.com
>     TO:    XXX at ourlocal.domain.com
>     Bcc:   someone at external.com
> I guess the letter of the of the law I should deliver the e-mail, to the 
> external address, since typo 's do happen, but there must be away round 
> it. May be I could not deliver Bcc if the to address is invalid?

First, if there is a "Bcc:" header in the incoming SMTP data, the  
server at the other end screwed up...the whole point of "Bcc:" is that 
other recipients aren't supposed to know about it.

Second, sendmail doesn't deliver based on headers from SMTP data...it 
delivers based on the "RCPT To:" command in the SMTP transaction.  So, 
whatever might be in a "Bcc:" header isn't going to do anything.

Now, if you have some program to deliver the e-mail locally that looks 
at headers and creates a new e-mail message if there is a "Bcc:" 
header, then that's the problem.

"sendmail -t" is an example of a command that does this sort of header 
parsing.  It's really only used for initiation of sending mail, and I 
think it's ignored when in daemon mode, but check to see if you are 
starting your daemon with this flag, just in case.

Jeff Rife |  
          | http://www.nabs.net/Cartoons/OverTheHedge/AntiqueOS.gif 

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