Then do the following:
Tick the box which says ‘use exchange’
Exchange username: your full email address
Exchange password: you email password
Exchange url:The url provided by your email host
Then click update and you should get a green banner at the top of the page confirming all settings were saved successfully.
Exchange url for Office 365 (non-private server): https://outlook.office365.com/ews/exchange.asmx
Exchange url for Rackspace Exchange: https://mex06.emailsrvr.com/ews/exchange.asmx
If you use Rackspace Exchange email you can find out which mex server number to use by logging into your email account at https://apps.rackspace.com and noting the url you are diverted to in the browser address bar, to log into the server.
If you are in doubt as to what to enter here, please contact our support team using the live chat button below your database menu or by emailing firstname.lastname@example.org