So another fun little learning lesson today with the new mail server.. I could send and receive emails internally no problem(sending from me@me.com to you@me.com) but the moment I wanted to send something from another mail server to the new one well it wasn’t having any of it.
As with all things there are always a million reasons for something to go wrong and mine was reason #445,002 
I ended up reading a thread that had enough similarities as me to open my eyes to what was going on. I had told postfix to have the smtp server on port 10587 for security reasons and in the end the MTA wasn’t setup to connect to that port.. Booerns. In the end I just said ‘stuff it’ and put it back to the default settings, so now my smtp server is running on the default 587 port and everything is working peachy keen. So if this is happening to you, go into your /etc/postfix/master.cf and anywhere you changed smoething like:
smtp inet n – n – - smtpd
into:
10587 inet n – n – - smtpd
go and change it back to the way it was and see if that resolves your issue
Well I woke up this morning to a wonderful surprise. It would seem that thunderbird misplaced all of my mail folders, or more specifically the GUI. The mail was there, thunderbird was receiving it just fine, it was even indexing it but the left hand side of my TB window was a big blank nothing. Couldn’t click on anything, changing the views didn’t make it re-appear, resizing it didn’t work, nothing.. The entire folder tree GUI was gone.
yourself the time of blindly copying and waiting for it to break. Because as soon as I saw the file Foldertree_json it became pretty apparent which file is responsible for building the folder tree 
