OS X Yosemite 10.10.3 Mail keep quitting unexpectedly. This started happening after the last update
I found the source of those repetitive crashes : a rule that tried moving email in a directory that does not exist anymore. Under 10.10.2 Mail would simply not do anything. Under 10.10.3 Mail 8.2 crashed and corrupt the mail index. Simply fixing the rules did solve my problem.