451 5.7.3 Cannot achieve Exchange Server authentication Error Exchange 2007
Posted on 2008-10-13
Im in the middle of an Exchange 2003 to Exchange 2007 transition, and i have come to an issue. Ill explain our mail setup, we have one exchange 2003 server which also hosts our spam filters (not a good setup but works for now). The spam filters on that machine has the smtp port set to 25 and i had to set the smtp port on exchange to 26, now with the exchange 2007 server added i cant send internal mail to the old exchange server it just sits in the que with this error "451 5.7.3 Cannot achieve Exchange Server authentication" now i have done some reading and found out that this probably due the the non standard smtp port that exchange 2003 is running on, as i have checked securities and authentication. Now what im asking is how do i tell exchange 2007 to send mail to port 26 on the old exchange server?