Cannot relay through Exchange 2010

Posted on 2012-09-05
Last Modified: 2012-09-16
I am having trouble sending an email through Exchange 2010.  I am testing with a telnet session from a Linux server, and have tried both with and w/out authentication.  Cannot figure out if the problem is my telnet/smtp dialogue, or the Exchange side.  On Exchange, I have set up a relay connector for the IP of the Linux server, as well as a user mailbox that I am sending from.  I have created a rule on the firewall to allow connections between both servers.  I have tried all combinations of authentication on the connector, and the only way I am able to send an email is with no auth on the telnet side, and also only if I send to an email address on the same domain that the connector is on (  When I try to send to an address on another domain, I get one of the following 2 errors:  When I try to send using AUTH LOGIN, and supply the base 64 username and passwords, I get similar errors.

SMTP -> ERROR: Password not accepted from server: 504 Unrecognized authentication type
SMTP -> ERROR: RCPT not accepted from server: 550 No such domain at this location

Here is the telnet session:

telnet 25
Connected to
Escape character is '^]'.
ehlo Hello [], pleased to meet you
250-SIZE 100000000
250 HELP
250 Sender <> OK
550 No such domain at this location
RCPT TO:<>        
550 No such domain at this location
250 Recipient <> OK
354 Start mail input; end with <CRLF>.<CRLF>
This is a test email.
250 Ok: queued as 664D2C96042
221 Goodbye, closing connection
Question by:cholmes28
    LVL 14

    Expert Comment

    Looks like the problem is on the Exchange side.

    (Based on this part of your telnet session:

    MAIL FROM:<>
    250 Sender <> OK
    RCPT TO:<>
    550 No such domain at this location            )

    It's likely the case that the connector you created for the Linux server to use is not set up correctly.  Try and see if you have set it up like this guy did:

    Accepted Solution

    Actually, I figured out the issue.  The relay connector was just fine, but the problem was in a bad route on our firewall, and also some configuration settings on the Barracuda spam filter.  Since the server sending the mail was on a different network, it had to pass thru the firewall and spam filter on the Exchange network before reaching the server.

    Author Closing Comment

    I only received one solution, and it was long after I posted question, and while the solution was a valid thing to check, it did not help me discover the solution. Weanwhile I continued to troubleshoot on my own, and ended up figuring it out myself.

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