Question problem with delete email

[mohammadmahdavi]

Dear all
i have a problem with outlook app and i'll be grateful if you help me to solve this problem.
The problem is that some of emails that i received, are deleting after reading. (reading using outlook or even other email applications on phone).
do anyone know what is problem?

 

[Ales]

The most obvious reason would be that one of the e-mail client applications is set to download and delete mail from the server.