>>>You need an email client
Er, no you don't! While businesses continue to use email clients, the vast of majority of individuals now access their email accounts via the web. (Only a minority of people continue to use email clients such as Outlook Express, Windows Live Mail or Thunderbird).
Primus doesn't even seem to what to let users know how to configure an email account with a mail client. (The 'automatic setup' feature, built into some email clients, only works with a fairly small number of email services). In the now somewhat unlikely event that the questioner's relative actually wants to use a mail client, the relevant details are as follows:
Incoming server: pop3.primusbroadband.co.uk ; Incoming Port: 110
Outgoing Server: smtp.primusbroadband.co.uk ; Outgoing Port: 25
Outgoing server authentication: On