Apple Mail app fails to connect with my iMac

My desktop will no longer send or receive emails.

Error Message: "Connections to the server 'p54-imap.mail.me.com' on the default ports timed out."

Mail provider is Apple, on 'me.com' and on 'icloud.com'.

OSX 10.11.6

I have not changed anything recently, as I use the iPad more than the desktop.

But my iPad works fine.

Thanks....

[Edited by Moderator]

Original Title: Apple mail not connecting.