User preference for default email to use

I setup ponymail to review some of the atlas/ranger apache lists.
I had to configure using my gmail account (no apache account yet)
However I am already a member of the mailing list using my company (ibm.com) account, so I figured I'd set that up as an additional address in ponymail. I did that association ok, but when I go into the compose window it will default to my authenticated email address, and I have to click the drop down to switch

Could we have a preference to allow the user to chose their default email -- of course this could be global, or could be related to group....

Start by tracing the compose window's sender-selection behavior and the existing additional-address association flow. Clarify whether the preference is global or per group, then verify that the selected default appears when composing and that users can still choose another associated address.

Written by the indexing model from the issue text.