Thanks. I figured as much but I figured I check since there could be buried treasures.
Any plans to add the ability to use an alias to send via SMTP? From a programming standpoint it should be relatively easy: The auth is using the mailbox credentials and that needn't change. If the Message From Name != Mailbox and From Name != (one of the aliases the mailbox is associated with) then reject the message. Otherwise, go ahead and send it.
This makes a lot of sense where you have multiple recipients for an alias within the same domain being able to respond as the alias instead of their individual identity. For example, Tony and Jeff receive for "email@example.com". Management may have software intercepting the mail to log and track progress, the communication log. Customers going directly to tony or jeff @dev.nul would break that process.
On a related note, how about adopting the Exchange and Google pattern for assigning aliases to the mailbox/user and calling the existing pattern a list or group?