Re: [Exim] Exim design flaw? (code 550 for bad sender addres…

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Auteur: Philip Hazel
Datum:  
Aan: Ralf G. R. Bergs
CC: exim-users@exim.org
Onderwerp: Re: [Exim] Exim design flaw? (code 550 for bad sender addresses)
On Wed, 19 Jan 2000, Ralf G. R. Bergs wrote:

> Ok, here's my question: Isn't it sort of a design flaw in Exim 3.03 that
> it's using reply code 550 (which indicates PERMANENT failure) for senders
> with bad addresses (if configured to reject these senders)?


No. Reject means reject. If you are going to refuse to accept an
address, what is the point of giving a temporary error code? The remote
host will just keep trying.

> I'm fetching my mail from my pop mailboxes using fetchmail 4.5.2. Fetchmail
> feeds the downloaded messages via SMTP to Exim. However, if there is a
> message with a non-valid sender address Exim correctly(!) refuses to accept
> it, BUT it replies with 550. This indicates to fetchmail a permanent failure
> (such as "mailbox not available,") and thus Fetchmal correctly(?) ceases
> further processing of mail for the respective recipient ("SMTP listener
> doesn't like recipient address `user@???.'")


That is an unfortunate interaction of the way Fetchmail works and the
way Exim works. Fetchmail is trying to be overly clever, IMHO. A sending
program should bounce a message if a recipient is rejected with 5xx, but
it shouldn't assume that this means the address is invalid for ever and
ever. New accounts get created, etc. So for another message, it should
try again.

Try using sender_reject instead of sender_reject_recipients. Maybe that
works better with fetchmail.

-- 
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.