(*
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