wordpress mailer (contact form 7): emails do not reach office 365 mailbox !

Hello,

Our company has recently changed all our email addresses from POP to Exchange Server (now using office 365).

We have got everything to work, except the form mailer on our Wordpress website (http://www.luminescence.co.uk/contact/).

The form mailer is an add-on to wordpress called 'Contact Form 7'.

If the form mailer is directed to send to a hotmail account or a different POP3 account, it works fine. The email from the form must be sending, however when it is aimed at one of our Office365 accounts, it doesn't appear in the Inbox folder OR in the Junk folder!

Any ideas?

Thanks

Karl