ProfiMail can work in two modes: Online (connected) and Offline (disconnected).
You can switch among modes in main menu of Account list.
Online mode
In Online mode, ProfiMail checks mail periodically as configured, and can keep permanent connections to selected accounts/folders.
Offline mode
In Offline mode, ProfiMail doesn’t connect automatically, but manual mail check is still possible, as well as downloading missing parts of messages (body, attachments).