I expect dropping into Java or running something like sendmail via a shell command are the Oracle-esque ways to go.
Something more cross-platform and conceptually straightforward would be to write the email to be sent to a queue table which included the from/to/body info, and have a scheduled AOLServer job process the queue every few minutes. There's not a lot of code in the queue processor function, because OACS has a pretty decent library for sending email.
