Install xfce4-mailwatch-plugin by entering the following commands in the terminal:
sudo apt update sudo apt install xfce4-mailwatch-plugin
Description:
mail watcher plugin for the Xfce4 panel
Mail checker panel plugin with support for local, POP3, IMAP, and Gmail accounts.
Homepage: http://spuriousinterrupt.org/projects/mailwatch
Version: 1.2.0-2ubuntu2
Section: universe/x11