Mail Rejected when we relay for a client.

11 msg	SMTP authentication with saslauthd against PAM
7 msg	Error in SMTP sequence
2 msg	dkim-milter on relay server unknown-jobid exter...
11 msg	Stubborn Cert issue
3 msg	Problems with false positives
4 msg	reject_unverified_recipient case sensitive?
3 msg	dkim=fail (verification error: invalid key gran...
5 msg	? Using header checks on (Postini) X-pstn-levels
2 msg	Can't find error in my config file. Can you?
1 msg	chroot postgresql ssl problem
15 msg	What cert to buy
3 msg	Address re-writing

Mail Rejected when we relay for a client.
\ Joey (11 Apr 2007)
. \ Noel Jones (11 Apr 2007)
. \ Sandy Drobic (11 Apr 2007)
. . \ Jesper Lund (11 Apr 2007)
. . \ Noel Jones (11 Apr 2007)
. . . \ Sandy Drobic (11 Apr 2007)
. . . . \ Joey (14 Apr 2007)
. . . . . \ Sandy Drobic (14 Apr 2007)
. . . . . \ Noel Jones (14 Apr 2007)

8 msg	Queueing up archive messages
2 msg	Cannot send e-mails from any e-mail clients
1 msg	Re: outbound mail failure - need to fix asap -S...
4 msg	outbound mail failure - need to fix asap
3 msg	Postfix alias problem
2 msg	problem to send a mail to a command in aliases
3 msg	smtpd_auth

Subject:	Mail Rejected when we relay for a client.
Group:	Postfix-users
From:	Joey
Date:	11 Apr 2007

Hi Everyone,

I have a situation where we relay mail from their own exchange server
through our postfix server. When the message gets sent to this specific
client their server rejects it.
From what I interpret from this error, it sounds like we are relaying the
message and making it look like postmaster sent the message and not the
actual sender which is joe.

1. Am I reading this correctly?
2. When we relay do we change the sender address somehow?

Apr 11 11:37:55 saturn postfix/smtpd[6174]: NOQUEUE: reject: RCPT from
dsl-17-41.cofs.net[68.142.17.41]: 450 <sarah.belle>: Recipient
address rejected: undeliverable address: host mail.anetwork.com[207.47.99.8]
said: 550 5.2.1 Mailbox unavailable. This server does not accept mails from
this sender address (postmaster). (in reply to RCPT TO
command); from=<Joe> to=<sarah.belle>
proto=ESMTP helo=<mail.impress123.com>

Thanks!

Joey