Applescript to set the flagged status of emails in the trash (Apple Mail)

Where are you getting errors?

I get an error enumerating all the Trash mailboxes since some accounts don't have a Trash mailbox.

Every account doesn't have a "Trash" mailbox, so you would need to test for that.

You could just wrap it all in a try as you don't need to process accounts without a "Trash" mailbox.

tell application "Mail"
	repeat with _account in imap accounts
		try
			set _inbox to _account's mailbox "Trash"
			set _messages to (a reference to (every message of _inbox whose flagged status is true))
			set _msglist to contents of _messages
			repeat with _message in _msglist
				--try
				set flagged status of _message to false
				--end try
			end repeat
		end try
	end repeat
end tell

What I posted worked for my iCloud account.

I don't know what to change, then, as it works on my iCloud account.