I'm using this paste technique to do a mail forwarding like OP but I'm using the second last paragraph of the email set to a variable as the comment text.
Watching it loop thru the messages I can see the text gets pasted for a moment and then deleted. The script delays for 1 second then does the next email. I'm not sending them just composing them in Mail.
What could be cuasing the comment text to disappear. Sometimes it stays mostly it gets deleted.
tell application "Mail"
try
set notes to {""}
set email_selection to (get selection)
repeat with a_msg in email_selection
set theText to content of a_msg
set their_name to words 2 thru -1 of paragraph 9 of theText
set comments to paragraph -5 of theText
set subscriber to paragraph 5 of theText
if comments ≠ "comments: " then
set comments_LF to (comments as rich text) & return
set the clipboard tocomments as rich text
copy {subscriber, comments as rich text} to the end of notes
set the_forwarded_message to forwarda_msg with opening window
tell the_forwarded_message
make new to recipient at end of to recipients with properties {name:"Alastair Leith", address:"alastair@publicland.com.au"}
set subject to (their_name as rich text) & " has a comment on subscription form"
activate
tell application "System Events" to keystroke "v" using {command down}
delay 0.1
end tell
end if
tell application "AppleScript Editor"
-- display dialog (notes as text)
end tell
end repeat
-- display dialog (notes as rich text)
return notes
-- display dialog notes
on error the error_messagenumber the error_number
tell application "AppleScript Editor"
display dialog "Error: " & the error_number & ". " & the error_message buttons {"OK"} default button 1
end tell
end try
end tell