Protocol used by Clearwell

Hello,

Hopefully a quick question. My organization is considering Symantec Clearwell for E-Discovery in our Microsoft Exchange 2010 environment. According to the Symantec representative it uses IMAP to access Exchange mailboxes and search them. However I find that difficult to believe since there are more efficient ways to do this like EWS or even MAPI. I read the public documentation but cannot get a definitive answer.

Can someone confirm what protocol/method does Clearwell use to access and search the Exchange databases for E-Discovery purposes?

Thanks.