I have noticed a problem with the icon of the plugin.
When my xfce session starts there isn't any network connectivity until NetworkManager connects to ethernet or wlan.
But the mailwatch plugin is launched nevertheless.
problem is, when the net connectivity is established, the 'forbidden' icon that appears on top of the enveloppe isn't removed. Everything else seems to work because i'm correctly notified of new mails via the 

notify-send -i stock_dialog-info "Nouveau Message" "Vous avez reçu un e-mail"

command i've set up