I have a EXCH 2000 SP3 server that is having trouble sending emails to some domains. Looking at the SMTP log files, an error occurs when using the BDAT command. It comes back "502 Command Unimplemented". The most common domains we cannot send to are: Hotmail.com and MSN.com. There are other domains that we can send messages to, but that we get errors in the log file. These errors occur when using the XEXCH50 command. Ther error say "500 Syntax error, command unrecognized". But, the message gets sent anyway. Does anyone have any suggestions? Thanks! Cory