Imap + sendmail bahavior

[Fields, David]

Hi,

I'm relatively new to using/running an IMAP server, but so far, I like what
I've seen from the Cyrus server.  I do have some strange behavior that is
puzzling me though.  I'm running this on my home server and it's just for
own personal use (I have my reasons), but I prefer using IMAP over POP3
because I have some software that allows my Outlook client and my Mutt
client to share the same mailbox.  At home, I generally use Outlook (yeah, I
know, it's full of bugs, but the interface still blows away pretty much
everything else out there).  When I'm at work, or at home, I use mutt to
read my mail when connection through my firewall.

However, ever since I moved to using IMAP, any time anyone tries to deliver
mail to mailboxes that don't exist on my mail server (and this happens a
lot), the mail server tries to send a response mail message back to whoever
it thinks sent the message.  With the way SPAM/Virus' work these days,
that's not really a good thing to do.  I would like to prevent this from
happening.

My configuration was with an older version of the IMAP server software (not
sure of the exact version since that machine died and I'm in the process of
rebuilding a new machine).  I was using the latest version of sendmail, but
I'm considering using Postfix on my new server.  If I remember right, this
did not happen at all when I was using sendmail and POP3.  It only started
happening after I moved to IMAP.  

If anyone has seen anything like this and knows how to prevent this, I would
appreciate any comments/suggestions you may have.

--
David Fields
david.fields at acs-inc.com

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