The SSB queues that Database Mail uses must first be enabled before you can send mail from a session. You do this by executing the
msdb stored procedure
sysmail_start_sp. This procedure is similar to its predecessor,
xp_startmail (as it must be called before sending), except that it has no parameters and, of course, has nothing to do with MAPI. It returns
1, indicating success or failure. If you don’t call this procedure, you receive this error message:
To temporarily disable SSB’s activation of the mail process, you execute
sysmail_stop_sp (also with no parameters), which returns
1. If you send mail from code after this ...