Im currently testing Thunderbird in combination with Microsoft's Office 365 (O365) and would like to write down some of my findings.
First of all Thunderbird does not natively support a direct connection to O365. You could still use imap for instance and receive your emails if this is not blocked by your admin.
But there is a nice extension called "owl" (just like the animal) which is maintained by a german company. This extension utilises the webinterface in the background to communicate with O365 which allows one to have more functionality, like calendars as well.
It is not for free, but this O365 is a enterprise product as well, I guess this makes just sense to keep the development ongoing.
What will you gain from switching to Thunderbird?
- Faster, more solid interface
- A working search function (sic!)
- Access to more usefull extensions to integrate lots of other stuff
What you might lose on the other hand... I'm not really sure yet, because I don't miss much so far! Maybe the access to the latest features (although I won't be missing their quick updates, which suddenly change the whole app design)?
One thing I have to mention is that the handling of different (text-based) signatures is not available out of the box. Thunderbird can basically only provide one signature per account currently.
For more you'll need an extension, but so far I did not find a feature complete one which I could use.
For some common features like shared mailboxes you might need to apply a workaround, because owl reassembles the features of the webinterface. Outlook usually automatically adds all the shared mailboxes you have access to as a seperate mailaccount in your folders list.
This is not the case for the webversion, where you have to add the shared mailboxes seperately. Therefore to make those available to Thunderbird as well you first have to add them to the webinterface (outlook.office.com). To do so, right click on the folders pane, then select "add shared folder or mailbox" and search for the mailbox. After a restart of your Thunderbird the shared mailbox should appear in the folder list.
I also want to mention some of the other extensions I use:
*cloud - FileLink for Nextcloud and ownCloud This one allows you to integrate your Nextcloud instance to share files directly. You can drag'n'drop files to email and it will automatically upload the file to your nextcloud and insert a share link to the email.
TbSync This is a tool for providing the possiblity to manage different cloud accounts. You can use this together with "Provider for CalDAV & CardDav" to sync with your Nextcloud calendar for example.
uBlock Origin Yes, you can finally block spam from html emails with the Thunderbird version of this famous extension.