My server is running Exchange 2000 with latest service pack on a Windows
2000 Server.
Occationally, I will receive reports from another company that they can't
send the email to my mail server. For example, I could find the following
entries in the smtp log.

2005-10-05 16:08:14 10.2.2.2 mail.some.domain.com SMTPSVC1 EXCHANGE 10.1.1.1
0 EHLO - +some.domain.com 250 0 0 SMTP -
2005-10-05 16:08:14 10.2.2.2 mail.some.domain.com SMTPSVC1 EXCHANGE 10.1.1.1
0 MAIL - +FROM: 250 0 0 SMTP -
2005-10-05 16:08:14 10.2.2.2 mail.some.domain.com SMTPSVC1 EXCHANGE 10.1.1.1
0 RCPT - +TO: 250 0 0 SMTP -
2005-10-05 16:08:15 10.2.2.2 mail.some.domain.com SMTPSVC1 EXCHANGE 10.1.1.1
0 xexch50 - +1932+2 504 0 0 SMTP -
2005-10-05 16:18:41 10.2.2.2 mail.some.domain.com SMTPSVC1 EXCHANGE 10.1.1.1
0 TIMEOUT - mail.some.domain.com 121 3290933450 625797 SMTP -
2005-10-05 16:18:41 10.2.2.2 mail.some.domain.com SMTPSVC1 EXCHANGE 10.1.1.1
0 QUIT - mail.some.domain.com 240 626766 625797 SMTP -

I have searched on the web for information and xexch50 with 504 is the
authentication error I believe. To my understanding, xexch50 is used only
between Exchange servers within the same organization. I found some
workarounds like disabling sending xexch50 command or use HELO instead of
EHLO, but these are the remote server's settings. What can I do on my server
to deal with this? Can I disable the advertisement of xexch50 command to
external domains? What's the common practise for this? Should I unregister
the dll for xexch50 or just stay with current condition and tell them to use
HELO instead EHLO? Thanks in advance.

Regards,
Steven T

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