We don't have a interface for Exchange online 365 however in general we suggest that rather than trying to develop interfaces for the various online mail providers such as Microsoft, Gmail and the like you use *web/email to send the emails with a BCC to the originating email account.
The originating emailing account can then add a message filter to store these emails in whatever folder they want such as the Sent folder.
The advantage with this approach is that it will work on any OS (Windows or Linux) and with virtually any email server (Gmail, Outlook, yahoo, or self hosted email server).
If you need to be able to access mail held in the users mailbox, PxPlus does include a POP3 interface that can provide you methods to read and process mails from any mail server that supports the industry standard POP3 interface.
If you do want to interface with Exchange Online, I believe there is a REST based API that you should be able to access using *plus/web/request.