procmail
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Re: filter number(_at_)foobar(_dot_)com

1999-08-06 13:54:37
On 6 August 1999, era eriksson <era(_at_)iki(_dot_)fi> wrote:
On Fri, 6 Aug 1999 08:03:30 +0300, Liviu Daia 
<Liviu(_dot_)Daia(_at_)imar(_dot_)ro>
wrote:
 > On 5 August 1999, Christophe Zwecker <doc(_at_)zwecker(_dot_)de> wrote:
[...]
 >> FYI: I need this for a cruising ship. Each guest gets a numer when
 >> getting on board, for that the number thingy. Since the email
 >> comes in thru a rather expensive satelite link, they need all
 >> attachments to be stripped.
 > been uploaded to your machine.  A much better way around this is to
 > configure your MTA to drop messages over a certain size, this way
 > the

Or otherwise do it from the MTA. Here are some stray thoughts,
although noting very disciplined:

  * If you can, create a virtual domain for all these users, then pass
  everything for this domain through its own mailer (this is Sendmail
  specific, obviously. Disclaimer: I'm a complete dilettante when it
  comes to Sendmail.)

  * Have a look at emil. This is an old monstrosity which isn't
  altoghether pleasant to deal with, but I think it will do what you
  want. It's heavy, but probably less heavy than Procmail plus the
  overhead of the inevitable external filtering.
[...]

    Emil can only re-encode attachments (which comes in quite handy when
you receive messages produced by Sun's MailTool brain damage), it can't
delete them.  Anyway, this still doesn't address my point: once the
message is queued to your system and sendmail starts messing with it to
attempt delivery and so on, it has already sucked your bandwidth.  The
only two ways around this are (1) IMAP, which can (theoretically) send
each attachment separately, or (2) reject large messages at the SMTP
negotiation stage, based on the SIZE parameter (which only works if both
your host and the remote one actually speak ESMTP).  For (1), you also
need a smart enough IMAP client.  (2) is a good idea even if you don't
have bandwidth restrictions.

    Regards,

    Liviu Daia

-- 
Dr. Liviu Daia               e-mail:   Liviu(_dot_)Daia(_at_)imar(_dot_)ro
Institute of Mathematics     web page: http://www.imar.ro/~daia
of the Romanian Academy      PGP key:  http://www.imar.ro/~daia/daia.asc