Rated 1 out of 5 stars

I'm running the new Tbird version 115 0b4 (Beta). Since the stock Get Mail icon/button is so tiny, I wanted to give this a shot. I use "Local Folders" for my folders. Good news: It works with 115 Beta. Bad news: It only works if you have previously selected precisely which inbox you want to use and have already fetched mail with the stock icon that is next to the blue "+New Message" button. Then this add-on will work as long as you have the Tbird open. If you close the program and re-open, then no go.
This add-on won't do a global "Local Folders" fetch upon startup. So I just used the "customize" function for the top main menu bar and added the stock icon with text on the left-side top to make the Beta more intuitive.

This review is for a previous version of the add-on (3.0.0). 

Please read the info given on the Add-on main page: "... only the accounts are checked for new messages for which you are authenticated (i.e. for which you entered your password)" and "it does the same as the default button 'Get All New Messages'."
If you are not satiisfied with that function, please don't blame my Add-on but reach out to the TB core team, e.g. via Feature Request in https://bugzilla.mozilla.org/describecomponents.cgi?product=Thunderbird

(By the way, if you tick the box in the password entry window "Use Password Manager to remember this password", then the TB stock button and my Add-on button will work as you want it to work.)