Apple mail, receiving email sporadically

Hi,

Having a problem with receiving emails regularly. I get them through on my phone straight away but very irregularly on my Mac. Running El Capitan 10/11/3.

I have tried off and on, switching offline/offline and running trouble shooting. In my email box there is often a warning triangle, when I click on this it says 

There may be a problem with the mail server or network. Verify the settings for account “xxxx.yyy

.co.uk” or try again.

The server returned the error: Connections to the server “pop.tiscali.co.uk” on the default ports timed out.

Very frustrating any ideas how to fix?