New email sending mode
In addition to smtp, php-mail and local file delivering method it might be helpful to add "database" method with corresponding task for scheduller extension. The point is simple - put into database whole letter for next background (async) sending with another method (can be smtp, php-mail or local file) and status reporting.
Why to do so? Answer is - insurance. It's very reliable. SMTP and plain mail func() can fail due to very various issues (server config, network timeout, ...), and realtime direct mail sending is slow. On the other hand - having system queue of letter and cron worker - any letter will be lost and we can control send-result of each.
Would that be interesting for community?