This plugin could be divided into several smaller plug-ins.
But the author did it all in one. This is his right.
I propose, in the info panel, on the main page of the plug-in to display next to the name of the mailbox,
number of new, unread messages.
In general, the plugin wery good!

The plugin is interesting, with a rich set of functions. However, there are small bugs. When you send a message with an attachment, the message in the Sent Items folder is not saved. This plugin is waiting for a good future.