Right now, you simply can't...

O365/Hosted Exchange environments DO support impersonation rights/delegation, so you could likely put something together that accomplishes what you are looking for on this. You can find more information on allowing the rights here: 

Once you have rights to all of the mailboxes from a domain administrator account of sorts I suspect you could then use that authentication (in code of your own) to facilitate authentication with the intended mailbox, then bring that data into the SmarterMail mailbox via a retrieval or migration task. 

Might be a lot of heavy lifting to facilitate the Microsoft authentication though. Have you checked with them to see if they have any prebuilt solutions/examples for that side of things? 

We do not find any prebuilt solution. Please suggest if you know any solution or service.

I think ST should build migration tool for such tasks. Afterall, they are the ones who will gain from it.

I'd be happy to get a feature request escalated on this for you! It would be great to be able to queue up migrations as an admin so that users don't even have to be involved.