DNS is done in the same place as the IP and other network settings.
CWIS > Properties > Connectivity > Protocols > IP (Internet Protocol) > DNS
For Office 365 servers the time needs to be within 2 minutes of the servers time.
And since they introduces SHA-2 encryption you must have a newer firmware to authenticate.
There is no issue on the later firmware emailing with smtp.office365.com:587 STARTTLS (Do not use the STARTTLS if available option)