Hi,

Yes you can certainly from SmartForms - https://community.nintex.com/t5/How-To/Integrating-K2-with-Microsoft-Teams/ta-p/125845

Pay close attention to the configuration sections as that can trip you up if you don't get it right.   

One of the problems that I encountered is that the token will expire, meaning that the user needs to authenticate again - which happens in the context of SmartForms OK as the authentication request gets made and the end user responds.  So I can happily send message to teams and individuals from a SmartForm as the logged in user.

If you are trying to do it from a workflow as the service account then this reauthentication isn't really possible as far as I can tell.  If anyone has a better solution / answer to this then please let me know!

Cheers,

Paul