When you have an email address associated with a web site, the service providers do not always permit you to use their smtp servers to send mail. The usual setup is to receive email from your website i.e.
[email protected] using the Easyspace pop server, but then when you reply to that message you need to have your own ISP to actually send emails. In my case I have a number of websites each with their own email address, but I then use my Orange account to reply to all the incoming messages - hope that clarifies.