I installed the public beta a couple of days ago. Since then, Mac Mail has been consistently freezing after about 30 minutes of use. It didn't freeze under 10.10.1. I haven't seen anyone else report a similar issue. I have Gmail, an Office 365 Exchange account with 30GB or so of mail, and an iCloud account. I've used MoreSpace to compress the Mail folder down from 35GB to 20GB - this hasn't previously caused any problems so long as Mail is not running during the compression. Anyone else experiencing this? Reports are automatically being sent to Apple every time I Force Quit Mail so I can reopen it.