[MlMt] Changing From address on a per-message basis?

[Mike Hucka]

I read Benny's announcement of a facility to have multiple SMTP servers: 
https://lists.freron.com/mailmate/2016-January/005366.html

I'm trying to do something similar, but there is a part that I can't 
quite figure out.  After adding a second SMTP server in my 
Submission.plist file and restarting, I do get the new pop-up in the 
Composer window.  However, Benny's description on the page above talks 
about being about to change the From address (apparently in the Composer 
window), but ... I don't see how or where.  This must be a really 
obvious thing that I'm missing because I'm too new to MailMate.

Attached is a screenshot of what my Composer window does show as the 
fields I can view or edit.  The From field is not listed there.

What am I missing?

Best regards,
MH
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