Joel Roberts:
> Hi all, new to the group. Have recently setup POSTFIX as an SMTP
> relay front end to an Exchange 2007 backend. Have encountered the
> following issue:
>
> I'm using POSTFIX as an SMTP fronted relay to an
> Exchange<http://www.tek-tips.com/viewthread.cfm?qid=1663396&page=1> 2007
> backend. The default size for attachments in POSTFIX is 10 MB.
> I've set that in the configuration file to be 20 MB. When I look
> at postconf -n it verifies that the limit is set to 20 MB,
> (message_size_limit = 20480000). I've stopped and restarted the
> postfix service, but messages are still bounced back to my Exchange
> server<http://www.tek-tips.com/viewthread.cfm?qid=1663396&page=1>
> as undeliverable if they exceed 10 MB in size.) The bounce-back
> message users receive lists the Debian Linux / Postfix server as
> the server bouncing it back for exceeding size. Is there somewhere
> else this needs to be set?
Attachments are MIME-encoded, which makes them significantly larger.
For example, a 10MB attachment becomes 13.3MB when it is encoded
with BASE 64.
If you believe that Postfix is in error then you must provide POSTFIX
logs and POSTFIX error messages, not the "user friendly" version that
Exchange users receive because that removes all the important details.
First, to verify that the limit is what you believe it is, try this:
$ telnet postfixserver 25
220 postfixserver ESMTP Postfix
ehlo whatever
250-postfixserver
250-PIPELINING
250-SIZE 20480000 <-- Your message_size_limit, not: 10240000
250-VRFY
250-ETRN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
mail from:<> size=20480000
250 2.1.0 Ok <-- Not: 552 5.3.4 Message size exceeds fixed limit
If the responses are not as shown above then you made a mistake in
the Postfix configuration file.
Wietse
