Unexpected service response

[Lowery, Michael]

I've never had a problem with the SMTP test before.  Now, testing a
postfix mail server, I get a Yellow alert, and the page says:

Service smtp on mail.domain.com is not OK : Unexpected service response


501 Syntax error in parameters or arguments



I can telnet to port 25 on this server with no problems from the hobbit
server, I get a 220 message upon connect.  Here is exactly what I get
(names and IPs changed to protect the innocent).  So what can be the
problem here?

[root at hobbit etc]# telnet mail.domain.com 25
Trying 20.30.40.51...
Connected to adsl-20-30-40-51.dsl.hometown.isp.net (20.30.40.51).
Escape character is '^]'.
220 SMTP service ready

Thanks,
Michael