POP3 settings not recognised.

I am trying to help a non-computer literate friend who has his own domain name hosted by names.co.uk. I have had to reload Windows 7 after a horrendous experience with Windows 10. I have set up EM client and have tried to enter the email settings for the Namesco server but EM client rejects the POP3 server settings. I have successfully set up these same details on his IPAD email so am now baffled as to why EM Client is rejecting the POP3 settings. Any suggestions would be most welcome.