I think you would have to match the message logs entries with the IIS logs ( assuming this is on-prem Exchange) for that user and the time sent.
How to determine which device sent particular email from Microsoft Exchange?
I understand that there were a lot of similar threads
Like this for example https://social.msdn.microsoft.com/Forums/en-US/2dd44e90-3021-44e6-a2ec-36ab61c2b27e/what-device-sent-an-email?forum=exchange2010
However my question is still a bit different. While in the tracking log you can find which type of cllient was used to send email (outlook, activesync or OWA) there is still no info about exact device (for example smartphone id) or client IP which sent the email.
If anyone could help to determine this I would be really appreciated.
Thank you in advance!