automatic set reply-to header in osx mail - macos

Question

I use a google account, say myaccount#google.com for work and I use aliases for the various projects I'm working on. Thus, for project1, I use myaccount+projet1#google.com, for project2 myaccount+projet2#google.com and so on. I do not need to add additional account in Mail since GMail ignores what's after the "+" sign.
Now, in the configuration of my mail account, I put all the addresses (including the ones with aliases) in the "Email address" field, separated by commas. So I can send a message from any of my emails myaccount+project*#google.com.
My question is about the "reply-to" header that I have to manually choose in order to receive the mail in the right folder. I looked in the settings and could not find a solution. Do you know any way to do it automatically (set the reply-to header the same as the from)? Apple script perhaps?
I know that I can use the "default write" command but that only allows to specify one specific "reply-to" header to all the emails, which is not what I'm looking for.
Thank you in advance.

Answer 1

Here is my WIP, I'm posting it now incase I never finish it. Hopefully I'll update this with an example that reads the required fields, rather than being hardcoded.
(3rd and probably final update)
Apologies if this doesn't do exactly what you need, but it did exactly what I needed, and I believe you requirements are simpler than mine.
-- Reply to current message with additional header changes.
-- (To be triggered from Keyboard Maestro, or ControllerMate on Alt-R)
-- function to read/focus/change data in message field
-- usage: set fieldValue to message_field("reply_to", false)
-- message_field("reply to", "moron")
on message_field(fieldname, newValue)
local tElements, tElement, tField, tValue, tClass
tell application "System Events"
tell process "Mail"
set frontmost to true
set tElements to scroll areas of window 1
repeat with tElement in tElements
set tName to get name of tElement as string
try
set tField to text field 1 of tElement
ignoring white space and punctuation
if (name of tField as string = fieldname) then
try
set tValue to get value of tField as string
on error
set tValue to ""
end try
set focused of tField to true
if (newValue ≠ false) then
set value of tField to newValue -- as string
end if
exit repeat
end if
end ignoring
end try
end repeat
end tell
end tell
return tValue
end message_field
-- split function (julifos # macscripter.net)
to split(someText, delimiter)
set AppleScript's text item delimiters to delimiter
set someText to someText's text items
set AppleScript's text item delimiters to {""} --> restore delimiters to default value
return someText
end split
-- Get information from current/selected message
tell application "Mail"
set theSignatureName to "Signature #1"
set theMessages to the selected messages of the front message viewer
set theMessage to first item of theMessages
-- Get the email address (ours, hopefully) the message was sent to
set theMessageWasTo to address of first to recipient of theMessage as string
-- Unfortunately, it seesm that Mail doesn't honour the existing Reply-To header
-- when a reply is triggered from a script, instead of from the Reply menu.
-- So here is a bit of a dance to get it.
set theMessageHeaders to headers of theMessage
try
set theMessageReplyToWas to first item of {reply to} of theMessage -- (thx to Brian Christmas)
tell me to set theMessageReplyToWas to item 1 of split(theMessageReplyToWas, ",")
on error
set theMessageReplyToWas to sender of theMessage
end try
-- you can also use: set temp to {deleted status, all headers, was replied to, flag index, date received, message id, background color, subject, read status, flagged status, message size, date sent, junk mail status, source, sender, was forwarded, was redirected, content} of foo
-- set Theheaders to all headers of theMessage -- If you want to get all the headers in text form and process manually
-- set mySource to source of theMessage -- If you want the message source
set theOutgoingMessage to reply theMessage with opening window
-- I want to set "Reply-To" to be the address the message was sent to
tell me to message_field("reply to", theMessageWasTo)
tell theOutgoingMessage
-- I don't like this, as it adds an extra recipient
make new to recipient with properties {address:theMessageWasTo}
-- so I'll do it my way
tell me to message_field("to", theMessageWasTo)
end tell
-- It's easier if you just want to change the sender or signature or something
-- set message signature of theOutgoingMessage to signature theSignatureName
-- set sender of theOutgoingMessage to "Federico Viticci "
end tell
-- Now all that remains is to set the focus back to the body of the message.