Have you ever seen this error when you have setup database mail:

The mail could not be sent to the recipients because of the mail server failure. (Sending Mail using [Account] ([TimeSent]). Exception Message: Could not connect to mail server. (No connection could be made because the target machine actively refused it

I have, and so have a few others based on my experience in the forums.  If you are like me, you immediately contacted you mail server administrator to find out why the mail server is refusing your mail.  Then once, they told you that there was nothing on the mail server that should be causing this, you tried using GMAIL/Hotmail and got the same error.  Now what do you do?  Fortunately for me I had a production server setup and working so decided to investigate differences.  Lo and behold, I found antivirus software installed on my desktop, but not on the server (let’s save that discussion for another time) So I looked in the antivirus log and, sure enough, mail being sent by database was being blocked by the “prevent mass-mailing worms” rule.  So I disabled the rule, and, viola!, mail sent successfully.  Of course the corporate antivirus policy almost immediately re-enabled the rule, but I had an answer.  I contacted my corporate antivirus administrator and had them add DatabaseMail90.exe (SQL Server 2005) to the exceptions list.

So if database mail is not working, check your antivirus settings.