When you register a domain, you are asked for some information to go in the public WHOIS records for that domain name. It's required by ICANN, the organisation responsible for the management of all domain names. Unfortunately, because that information is public, sometimes spammers get hold of it.
Fortunately, there is a solution. On most of our domains, you can enable WHOIS privacy. It's £3 per year, or free for .uk domain names (as required by Nominet), and means that your WHOIS information isn't publicly displayed when people look up your domain name. Instead, they'll see "Contact Privacy Customer 1234567890" (we use the number to keep track of whose mail should go where, but it's not publicly identifiable as you), and a forwarding email address such as firstname.lastname@example.org. There will also be a phone number on there that goes straight to voicemail.
We'll filter out as much spam as we can, but if someone has a legitimate reason to get in touch with you, we'll try and forward you whatever they have sent to our contact privacy team. If you have any more questions, or would like to set up WHOIS privacy on your domain, just let us know at email@example.com or by opening a ticket.