Customised IMAP server

Hi,

I have already setup O365 E1 Plan and everything is working great. I had mapped mail.domain.com (assuming domain.com is my domainname) to outlook.office365.com for incoming server and also smtp.domain.com to smtp.office365.com for outgoing server. No issue, just that Outlook keep prompting to the SSL cert. Is there a way to store the cert and stop the prompting?

Thanks

NC