List:
> I wanted to confirm the behavior we are experiencing at the moment when
> delivering messages to addresses aliased to thousands of local users.
> For example we have the address distgr...@domain.tld which is an alias
> to 3000 local users. When our inbound spam filter connects to the
> Postfix server to relay a message to this user we are seeing a timeout
> after 60 seconds and the message gets deferred on the filter, but the
> message has actually been delivered to the alias and subsequently all
> the recipients. The filter then retries the deferred message and we
> start having duplicate messages to the users.
This problem is described inm RFC 1047 (Duplicate Messages and
SMTP). The document was published in 1988, but apperently not
everyone who needs to know has gotten it.
> Is it true that Postfix is waiting to send 250 OK back to the filter
> until all the recipients have had a copy of the message delivered to
> their inbox? If so is there a more efficient way to go about delivering
> to many thousands of aliases?
As required by SMTP, the SMTP client MUST wait until the server
replies to the end-of-data indication ("." on a line by itself).
You can work around a slow SMTP server by by reducing the number
of recipients per MAIL transaction. Postfix by default sends no
more than 50.
Or you can fix the SMTP server so it responds in a reasonable time,
Wietse
