I took a stab at improving the applescript/Automator based workaround to this. My improvement is added as a comment to http://techpatio.com/2012/guides-how-to/mountain-lion-mail-default-from-field-se nder-bug but also included below in verbatim for convenience and reference.
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Since I really needed to fix this (the bug is driving me insane…), I took a stab at your wishlist and also fixed some other annoyances (sometimes your original script included the body of the original message twice for some weird reason).
There is still one really annoying behavior; “selection” only picks the first message in a thread even though another message is selected. I can’t figure out how to fix this, but the manual fix is to double click the message so that it comes up in a separate window, then the script works ok.
So, after a lot of hacking, I came up with the script below (to be used from Automator). I then use system preferences to bind this script to Cmd-R (add it to “Application Shortcuts” for “Mail.app” in “Keyboard” -> “Keyboard Shortcuts”.
Note that to get “Reply All” behavior, you replace
set theReply to reply selectedMessage
with
set theReply to reply selectedMessage with reply to all
I created a copy of the script for this and mapped it to Shift-Cmd-R
Here is the script:
on run tell application "Mail" set theSelection to selection if ((count of theSelection) > 0) then set selectedMessage to item 1 of theSelection set addresses to address of every recipient of selectedMessage set sentTo to "" repeat with selectedAccount in accounts set accountemails to email addresses of selectedAccount repeat with accountemail in accountemails if addresses contains accountemail then set sentTo to full name of selectedAccount & " <" & accountemail & ">" exit repeat end if end repeat end repeat set theReply to reply selectedMessage tell theReply to set sender to sentTo tell theReply to set visible to true else display dialog ("Select a message before running this script.") end if end tell end run