All works well, except that 'Fwd:' in the subject line, which I'd like to remove when forwarding
tell application "Mail"
set theMessage to item 1 of (get selection)
set forwardedMessage to forward theMessage without opening window
tell forwardedMessage
make new to recipient at end of to recipients with properties {address:"a@b.com"}
set message signature of forwardedMessage to signature "Blank" of application "Mail"
set stringLength to (count subject of forwardedMessage)
set subject of forwardedMessage to (characters 0 thru stringLength) as string
send
end tell
end tell