Emails from a specific person are being deleted or disappearing from my inbox.

I have checked sorting rules so know thats not causing it.  I have also changed my password and made sure that my phone can not be deleting them, as they'd go to the POP folder.

The emails are still being removed from the inbox though - I'm guessing when they have replied too?

I know you can click conversation to see last emails... but it does not allow you to access the "attached files" because the email you were replying too is gone.

Could I please have a history of logins to the account (IP) for the last month?
Also, if I give the email address to support... is it possible to see what happened to the emails & how?