All my Internet Accounts Disappeared
I normally have about a dozen email accounts, because I have my own domain name with several email addresses, two ISPs, each with a few email addresses, a gmail address, an Apple address, and so on.
A few minutes ago, when I tried to check my email, these email accounts were all gone, inbox almost empty. Normally, there are a few thousand messages archived in my inbox. Investigating, I find none of my email accounts appear in System Preferences: Internet Accounts.
I rebuilt permissions, checked the hard drive, restarted. All seems well. I can't understand how this could have happened. I was able to restore one of my gmail addresses and my iCloud address, but I don't use these accounts much.
All my emails, and probably other account information, are still on the hard drive in MyAccount: library: Mail:V2
I can't understand how or why this happened. Nothing like this ever happened before. The machine works fine in other respects. Yosemite 10.10.3, a late 2009 MacBook with plenty of RAM. These accounts were working last night. I don't remember doing anything unusual.
I can probably restore these accounts, as I have records of email addresses, passwords and so on, but it will be laborious, and I'm worried the new accounts won't link up with the thousands of saved messages stored on the hard disk in library:mail:V2
I'm fully backed up on an Airport Time Capsule, but I've never restored from a backup device like this, and dread making a mistake.
Advice gratefully accepted. I might need a lot of it.
MacBook, OS X Yosemite (10.10.3), 8 GB RAM