Mail accounts
I am not sure with pipex....
Alot of ISP's allow you to keep your mail box for an annual fee but dont advertise it as a product to sell because of setup costs.
When I moved from Globalnet to another ISP I contacted globalnet and they offered me their just-mail product (it's not advertised) which meant I could keep my full pop3 mail service and also my webspace with them for an annual fee of £14 - money well spent considering I have had the email address for over ten years and lord only knows who may have it that I have not spoken to in a while.
All in all for under or around £20 a year it would be worth keeping it on if you have had your email addresse(s) a while.
There is an issue if you do keep the mailbox then you should still be able to receive the mail, smtp sending will be blocked because your not on Pipex's network (this is to stop spammers and may be permitted if you authenticate with your current username/password to the smtp server whilst on an alternative ISP). Using your own SMTP server is more than likely not an option as most spam filters will look up the IP Address of the isp your sending from and see it is not Pipex and junk the mail - so you may have to resort to sending via pipex's webmail client if you want your emails to appear as from your old account or from a different email provider altogether.
Cheers