Very useful and clear reference Greg, nicely illustrated too, I hope the guys think it's worthy of inclusion in next year's 'Best of' publication - I can never find this information when I need it. 

One thing I'd like to point out as a useful addition to it is an article that Microsoft published at : http://support.microsoft.com/kb/311231/EN-US/

Point Q7 is worth reading, as it recommends that you only connect to a POP3 server on your local network, because using a server hosted by an ISP may prove unreliable and cause SQLMail to hang, which requires a restart of SQL Server if you want to send mail again.