Sometimes the data file for a mailbox can get partially corrupt. Common examples are clicking on an email then only to show a blank screen or clicking on an email in a folder listing only to show the wrong email after.
Below are two articles that can help both Outlook and MacMail users.
How to use Rebuild for MacMail
- Select the Mailbox
- Choose Rebuild from the Mailbox menu
- There is a rebuild option for every IMAP email client because this happens to everyone at some point