If you’ve been using Apple or Mac mail for years like I have you’ve probably had the same frustration that comes with a ridiculous load time for the app itself. It sometimes took 5 minutes to start up before I could actually read mail. I had archived old messages and deleted everything I could but still no luck. And then I found this excellent tip on basically rebuilding the behind the scenes sql database. It worked well. Still takes a minute to load but it’s much better than before. The gist is…

First quit Mail – then:

For OSX Lion (10.7) and Mountain Lion (10.8) you need to do the following:

1. Open the Terminal App – You can find this by using spotlight and typing terminal.
2. Copy and paste this command into the command line of Terminal:
   sqlite3 ~/Library/Mail/V2/MailData/Envelope\ Index vacuum;

For Snow Leopard (10.6) you need to do the following:

1. Open the Terminal App – You can find this by using spotlight and typing terminal.
2. Copy and paste this command into the command line of Terminal:
   /usr/bin/sqlite3 ~/Library/Mail/Envelope\ Index vacuum;

You can find the original article here: http://www.fixkb.com/2013/03/apple-mail-application-very-slow-to-respond.html