Check for new emails at regular intervals:

Enables background checking for new emails: If PopMan is minimized, it will check your email accounts for new mail at regular intervals. "Time slice" allows you to specify this interval.

Acoustic notification:

Specifies whether an acoustic notification occurs when new mail arrives.
"Sound file" enables you to enter any WAV file that you want to hear in this case.

Show balloon tip:

Specifies whether a balloon tip will be displayed when new mail arrives (only available on Win ME, WinNT 5.0 or better!):