You'd need to write your own mail protocol host/gateway on top of this service... Pop/smtp/imap, etc. Also, search is a bigger/harder issue to solve, assuming

You'd need to write your own mail protocol host/gateway on top of this service... Pop/smtp/imap, etc. Also, search is a bigger/harder issue to solve, assuming you want to support clients searching for emails without a full scan of their mailbox for matches.