Rebuild Apple Mail Mailboxes

I have not reported on the Apple Mail App recently, but rest assured it is still having problems galore. I have been following an article online where a person was having problems with Apple Mail. When he tried to access a certain folder in Mail, then Mail would crash. He was trying to use the “Rebuild” command in Mail to rebuild that folder or account, a very good idea. However, the App would crash before he could do the Rebuild.

Onyx Rebuild Rescue

This person was looking for help in finding a way to rebuild the Mail mailbox Index outside Apple Mail. By the way, this person was running macOS Sierra 10.12.6. I seemed to remember the excellent Onyx utility having a feature that would Rebuild Mail’s mailboxes. I booted into my Sierra install (I keep if for testing purposes like this one) and opened Onyx:

Onyx Maintenance

I searched around a bit and found the Mail Rebuild in the Maintenance Tab. So, I replied to this person and told him about installing the Sierra version of Onyx. I also cautioned him that he might wish to uncheck all the other stuff in this window if he did not wish to run those functions. I advised this person to be sure and do a Restart on their Mac after running Onyx, then boot up Mail and see if the crash issue was fixed. I have not heard back if he did this or not, but if you are having an issue like this with Apple Mail with it crashing, then a mailbox rebuild is one of the main troubleshooting methods for sure.

If you happen to be running macOS High Sierra then your version of Onyx Mail Rebuild will look like this:

Onyx Rebuild

The same caveat applies, if you do not wish to run all the other stuff in this window, simply uncheck them. Once Onyx is finished with this routine, be sure and Restart, then give Mail a try.


I no longer use Apple Mail, but I know many people do use it. These Mail repair functions are built into more than one Mac utility App for a reason, Mail just has issues from time to time.