Apple Mail hides mail received on multiple addresses Recently I've noticed that if I'm sent an e-mail on multiple addresses for which I have accounts set up in Apple Mail (macOS or iOS), the Apple Mail client will only display only one of these mails, and provide no access (other than explicitly selecting to view one account) to the others. Moreover I can't choose which account's mail is displayed (and it can be different on macOS and iOS). 

Is this the intended behavior? Is there a way to restore the normal e-mail client behavior of simply seeing all the mail I've been sent?
Many common Apple mail issues can be fixed by rebuilding the Envelope Index.

MAKE SURE YOU HAVE CREATED A BACKUP, FIRST. YOU HAVE BEEN WARNED!


Quit mail.app
Hold down the Option key, then in the Finder choose Go > Library.
In Macintosh HD/Users/yourname/Library/Mail/V2/MailData, move all files starting with “Envelope Index,” such as Envelope Index or Envelope Index-shm to your Desktop.
Launch Mail and it will build new Envelope Index files -- this step could take a long time.