There are couple of directions that may cause missing emails:

  1. Do you use also PC / Web clients for your account? If so, is it possible they are configured to POP3, and hence “pull” and delete the mail from the server (as POP3 often does). If this is the case, you just need to configure your PC client to “leave messages on the server”, or even better, switch to IMAP. Also, look at your account settings on that issue.
  2. Please check if you do not have rules that somehow move the emails to other folders. You can search on your stock client to find one of those missing emails, and if it is not in the inbox, look in TypeApp in that same folder.