SFB Missed Conversation email trace

[Deleted]

Hi,

Does anyone know the origin of the SFB 2015 (On-Prem) 'Missed Conversation' emails. 

Does the message goes from our SFB onprem to exchange onprem (and then to User) or does sfb onprem sends this message to exchange online (O365) and then to user's inbox?

Thanks in advance.

[#2]

I have found out that this Missed Conversation emails are being sent from SFB to EWS directly which bypasses office 365 completely. Which is why we cannot run a successful trace to these accounts.