Highlighting important Gmail messages in Mail

AppleScript
#1

I’m writing a Mail Rule that highlights important Gmail messages in Apple Mail. The best I’ve been able to come up with so far is:

-- Copyright 2022 Google LLC.
-- SPDX-License-Identifier: Apache-2.0

use AppleScript version "2.4" -- Yosemite (10.10) or later
use scripting additions

-- uncomment when running interactively
--tell application "Mail"
--	set theSel to selection
--	set theMailbox to "email@example.com"
--	set theRule to "Rule 2"
--end tell
--
--using terms from application "Mail"
--	perform mail action with messages theSel in mailboxes theMailbox for rule theRule
--end using terms from
-- end uncomment when running interactively

using terms from application "Mail"
	on perform mail action with messages messageList in mailboxes mbox for rule aRule
		repeat with theMessage in messageList
			set received to date received of theMessage
			repeat with importantMessage in messages of mailbox "Important" of container of mailbox of theMessage
				if (id of importantMessage) = (id of theMessage) then
					log "important"
					set background color of theMessage to yellow
					exit repeat
				end if
				
				if (date received of importantMessage) < received then
					log "out of candidates"
					exit repeat
				end if
			end repeat
		end repeat
	end perform mail action with messages
end using terms from

It works, but it can delay incoming mail by several seconds, and makes Mail less responsive to typing as it’s running. I’ve tried two things to speed it up, which have not worked:

  • looking up messages by ID: the script doesn’t compile. I’ve posted this as Unable to look up messages by id from mailboxes in Mail

  • using a filter expression:

    -- Copyright 2022 Google LLC.
-- SPDX-License-Identifier: Apache-2.0

using terms from application "Mail"
    on perform mail action with messages messageList in mailboxes mbox for rule aRule
        repeat with theMessage in messageList
            local importantMessages
            tell mailbox "Important" of container of mailbox of theMessage
                set importantMessages to (messages where id is (id of theMessage))
            end tell
            if not importantMessages = {} then
                set background color of theMessage to yellow
            end if
        end repeat
    end perform mail action with messages
end using terms from

    which works when run interactively, but hangs Mail when run as a Mail Rule.

Do you have any ideas why these have failed, or ways I can make the original script work more quickly as a Mail Rule instead?

#3

Does something like this perform better:

	repeat with theMessage in messageList
		if name of mailbox of theMessage is "important" then
			--do something
		end if
	end repeat
#4

I haven’t gotten that to work; Script Debugger shows each message’s mailbox name as “[Gmail]/All Mail”, even when it is also contained in other mailboxes.