Rebuild & Reindex messages in Mail.app

For some reason Mail.app will stop finding messages, or just crashes, or … In order to fix this, I execute the following steps:

1. Close Mail.app
2. Open Terminal
3. Enter: cd ~/Library/Mail/V4/MailData/
4. Enter: rm Envelop\ Inde*

Remark: This is just a post for myself, so I don’t spend time looking for the correct files to delete.