We would love to give you a simple, definitive answer to this question,. But unfortunately, it depends.
First, please choose if you are using Microsoft 365 or an Exchange onPremise server.
You have the choice how to use our add-in, depending on your individual requirements.
The COM add-in supports some features which are not supported with the Office add-in. If you do not need the features being available with the COM add-in, we strongly recommend using the Office add-in, since it’s much more lightweight.
If you need the features of the COM add-in, you basically can decide if:
You only want to use the COM add-in (only works on Windows)
You want to use both - COM add-in on Windows and Office add-in on iOS/Android/Web
If you want to use both, we recommend hiding the Office add-in in Windows, so you do not end up with too many buttons.
You can check the differences here.
Depending on your exact Exchange version and Outlook client version, you may be able to use the Office add-in. We do not recommend this though, since we have customers who had issues get it running.
We recommend that you use the new COM add-in.