If you have trouble sending messages using DatabaseMail and are getting "13 error 2005-12-22 13:49:17.053 The mail could not be sent to the recipients because of the mail server failure. (Sending Mail using Account 1 (2005-12-22T13:49:16). Exception Message: Could not connect to mail server. (An established connection was aborted by the software in your host m 3640 5 NULL 2005-12-22 13:49:17.053 sa" This output came from this query SELECT * FROM msdb.dbo.sysmail_event_log
Take a look at your virus scan properties -- Prevent mass mailing worms from sending mail. I had to add DatabaseMail90.exe to the exclude list before it would let DatabaseMail mail through.
Database Mail Setup