First my apologies if this has been asked before and is somewhere else on the forum but the search facility didn't find it.
Our email administrator has changed the default IMAP + SSL port from 993 to 1143 (please don't ask).
Having set this port in Alert Central - see below - I'm not convinced it is taking the setting as every time you return to the page the default port 993 is inserted.
Am I correct with my suspicion on the behavior?
Your 1143 port will be stored in database and used as your incoming email port when you click "Next" button in Getting Started wizard or save settings on Email Server Settings page http://[YOUR IP ADDRESS]/index.html#settings/email-server/. When you return back to Email Settings page default SSL port is displayed but it will be saved only in case you click "Save" button or "Next" button in Getting Started Wizard.