550 5.7.1 Unable to relay

[Ben]

We're getting the "550 5.7.1 Unable to relay" when using POP client (from external of network) to our Exchange 2003 server. We've already enabled "relay authenticated users.

Please help.

[Michael Lamberson (MVP)]

Have you set the client properly?
XCLN: Routing Restrictions Require SMTP Authentication
http://support.microsoft.com/default.aspx?scid=kb;EN-US;197869


On Sat, 20 Dec 2003 06:16:08 -0800, Ben

We're getting the "550 5.7.1 Unable to relay" when using POP client (from external of network) to our Exchange 2003 server. We've already enabled "relay authenticated users."
Please help.

[Ben]

Yes, we have set up the client properly (the "My server requires authentication" is enabled). It was all working before we migrated from Exchange 5.5. We are using Outlook 2002 & 2003 clients.

[Al Mulnick]

Wow. Can you repost the original problem?


Al

Post by Ben
Yes, we have set up the client properly (the "My server requires

authentication" is enabled). It was all working before we migrated from
Exchange 5.5. We are using Outlook 2002 & 2003 clients.

[Alan Malmberg [MSFT]]

I never did see are you using a firewall? If so, does it answer with an
SMTP proxy? If so, the auth and auth=login commands are probably getting
stripped by the firewall. Most proxies are basic SMTP (7 verbs). Exchange
2000 and 2003 allow 18 verbs including ESMTP. Auth and Auth=login are
extended SMTP commands. Also, Exchange 2000 and 2003 are locked down for
relay by default to only allow authenticated users to relay. Exchange 5.5
could be locked down, but was open out of the box.

==========================================================

Alan Malmberg, MCSE:Messaging
Microsoft Exchange Support

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This posting is provided "AS IS" with no warranties, and confers no rights.
==========================================================

[Mark Fugatt [MVP]]

Are you running a PIX firewall?
--
Mark Fugatt
Microsoft Exchange MVP
www.exchangetrainer.com
www.msexchange.org

Post by Ben
We're getting the "550 5.7.1 Unable to relay" when using POP client (from
external of network) to our Exchange 2003 server. We've already enabled
"relay authenticated users."
Please help.