Apple Mail Crashes on startup

If Apple’s mail app crashes on startup, then force a rebuild of its database by removing this file and any other files with the same prefix : 
 /Users/<username>/Library/Mail/V2/MailData/Envelope Index 
 There may be multiple Envelope Index temp files present. This delete command will remove all of them. 
 rm -f ~/Library/Mail/V2/MailData/Envelope\ Index*