Software

all email or some email?

If some emails get a 550 error. Your server may be black listed. If so the rest of the 550 error should tell you how to be removed from the blacklist. You may be blacklisted if you have a dynamic address or if your on adialup. Contact the administrator on the other side to see why the 550 is occuring.


IF all emails, uncheck the reverse lookup checkbox in the virual smtp server, under the system manager and see if it helps.

in case you are using two different internet providers, your problem will most probably be due to the fact that one provider excludes the other one. (question of competition)
I had the same and had to de-activate one provider to receive all my mail.

Good luck

Your ISP needs to set his network up to transmit your SMTP mail. Your DNS likely is also misconfigured if the name lookup fails. Is your Exchange set up for POP authentication? Have your users check their mail before trying to send. There is a setting in Outlook XP (My server requires authentication").

The server may require authentication. On the client side check under Tools / Accounts (or Services) and then Properties of the mail account. Go to the Servers tab and click the box that says "My Server requires...".

You want to block any unauthorized relaying. There is no sense in trying to get un-blacklisted until you do that. We were blacklisted for this very thing (only GroupWise on NetWare server) and it took quite a while to get off the list. See the Microsoft document "Controlling SMTP Relaying with Microsoft Exchange":
http://www.microsoft.com/technet/treeview/default.asp?url=/technet/security/prodtech/mailexch/excrelay.asp

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