The new law -- which is Britain's implementation of the EU Privacy and Electronics Communication Directive, and comes into force on 11 December -- makes it an offence for a UK company to send junk email or text messages, unless the recipient is an existing customer or has given their permission to receive such material. Firms who flout the law could face a £5,000 fine for each breach.
However, only personal email accounts will be covered. It will still be legal for a company to send unsolicited commercial messages to corporate email addresses.
According to the Department of Trade and Industry (DTI), this decision was taken so that "legitimate business to business communication" was not hampered. This may be little consolation to UK workers who find their inboxes full of adverts for Viagra, debt-relief plans and pills for "physical enhancement", but the DTI insists that during its recent consultation on the EU directive, many businesses said they didn't want to lose email as a marketing tool.
E-commerce minister Stephen Timms believes this legislation is an important step in combating the growth of spam, which is now thought to make up at least half of all email received in Britain.
"I think this is a pretty effective method for addressing intra-EU spam," Timms told a group of journalists on Wednesday. He added, however, that the new legislation wouldn't be enough on its own to stop the problem.
Timms explained that it was also important to educate users on how to cut down the amount of spam they receive, and to take an international approach to the issue.
This last point carries considerable weight, as there is concern that the US is taking the wrong approach to spam regulation. While the EU directive has pushed for an opt-in system, America looks to be on course to introduce legislation that would put the onus on individuals to opt-out of receiving unsolicited email from companies.
Experts have warned that this could lead to the meltdown of the Internet as a communications medium, because it would effectively legitimise spamming.
Timms did not criticise the US' approach to spam, and said he was encouraged that moves were being taken to address the problem.
"I hope we can have a good dialogue about how we can take action that is effective for both of us. We've got a lot to talk about," Timms told ZDNet UK.
With so much spam coming from outside of Europe, there have been claims that the European directive -- and the UK's implementation of it through this new legislation -- will only have a limited impact.
The new laws will also cover cookies, which are small files that are placed on a user's hard drive by a Web site to help it to identify the user. Web sites will now have to clearly identify when they operate a cookie, and will have to allow users to switch them off.