When email messages (that you have not deleted) go missing from your Inbox, the most likely cause is that your email client is set up to use POP, which is a protocol that downloads messages to your computer while removing them from the email server.
To prevent email messages from disappearing from your Inbox in
the future, we recommend you configure your email
client to use IMAP, a protocol that leaves your email on the
Sometimes UB can restore email messages from your Inbox from backups. To attempt to recover Inbox items, submit a file restore request (login required).