Speed up Mail.app

speedmail.applescript

(*
Speed up Mail.app by vacuuming the Envelope Index
Code from: http://www.hawkwings.net/2007/03/03/scripts-to-automate-the-mailapp-envelope-speed-trick/
Originally by "pmbuko" with modifications by Romulo
Updated by Brett Terpstra 2012
Updated by Mathias Törnblom 2015 to support V3 in El Capitan and still keep backwards compability
Updated by @lbutlr for V5 and Container folder in High Sierra and use du
*)

tell application "Mail" to quit
set os_version to do shell script "sw_vers -productVersion"
set mail_version to "V2"
considering numeric strings
	if "10.10" ≤ os_version then set mail_version to "~/Library/Mail/V3/Maildata/Envelope\\ Index"
	if "10.12" < os_version then set mail_version to "~/Library/Mail/V4/Maildata/Envelope\\ Index"
	if "10.13" ≤ os_version then set mail_version to "~/Library/Containers/com.apple.mail/Data/Library/Mail/V5/Maildata/Envelope\\ Index"
end considering

set sizeBefore to do shell script "du -h  " & mail_version & "|  awk {'print $1'}"
do shell script "/usr/bin/sqlite3 " & mail_version & " vacuum"
set sizeAfter to do shell script "du -h " & mail_version & "| awk {'print $1'}"
display dialog ("Mail index before: " & sizeBefore & return & "Mail index after: " & sizeAfter & return & return & "Enjoy the new speed!")
tell application "Mail" to activate

This script is not compatible with oldest version (before 10.10). To allow this, you need to change the line set mail_version to "V2" by set mail_version to "~/Library/Mail/V2/Maildata/Envelope\\ Index"

It seems the script does not work on Mac OS 10.14 Mojave, but I don't understand why.
I added the line if "10.14" ≤ os_version then set mail_version to "~/Library/Containers/com.apple.mail/Data/Library/Mail/V6/MailData/Envelope\\ Index"

but running the script gives the error :
Error: unable to open database \"/Users/MyName/Library/Containers/com.apple.mail/Data/Library/Mail/V6/MailData/Envelope Index\": unable to open database file" number 1

However, the path seems correct.

Setting "~/Library/Mail/V6/Maildata/Envelope\\ Index" instead of "/Users/MyName/Library/Containers/com.apple.mail/Data/Library/Mail/V6/MailData/Envelope Index\" gives the same error.

I'm seeing the same issue on Mojave. I haven't found a solution yet.

This happens because of security measures. Open System Preferences -> Security & Privacy -> Privacy tab and grant "Full Disk Access" to Terminal.app or the automator, where ever you run the applescript.

Dont forget to revoke permissions after you finished reorganizing the index.