[Exim] Exim design flaw? (code 550 for bad sender addresses)

Hi there,

first I'm asking that you cc me in your replies since I'm not subscribed to
this list. Thank you.

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)?

I'm currently facing the following problem and don't know who to blame (:-):

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@???.'")

Isn't it Exim's fault that this doesn't work? Shouldn't Exim better reply
with a code of 450 instead of 550?

Thanks for your comments,

Ralf

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