How can I keep someone from contacting me in email or instant messaging?

For email, the most radical solution is to change your email address - or rather, disable the email address that the person is using to try to contact you. That's a fairly harsh solution because it means that you then have to go and tell everyone else from whom you actually want email your new address. If you do end up going this route I definitely recommend following some of the recommendations in this previous article to make the next time you need to change a whole lot easier.

If changing your email address isn't something you want to consider just yet, then the next best thing is to never see the email you don't want to see. In other words, filtering. Most email clients have the ability for you to set up rules or filters that will take action on an email when it is recieved. So use your email program to set up a rule that says, in essense, "if I get mail from this person, delete it immediately"

If your email client doesn't have rules or filtering built in then you might check with your ISP. Many ISPs now offer web based access and quite often that includes filtering as well. By setting up a filter directly with your ISP, the email you filter out will never even be downloaded.

As an almost draconian measure, many web email services such as Hotmail or Yahoo Mail, as well as some mail clients now have spam filtering options that allow you to reject email that isn't from an address in your address book. This means you'll accept email only from people you know. There are serious drawbacks to this approach, since there's often a lot of legitimate email that arrives from addresses you don't know beforehand such as on-line purchase confirmations or other ecommerce and business correspondence. But it can be an extreme solution.

Finally, if it's serious enough check with your ISP or the ISP of the person who's sending email for any additional alternatives they might have to offer. Depending on the ISP they may be able to help.

If much of what I've just described sounds familiar it should; these are similar to many techniques used to fight spam. In both cases you're receiving unwanted email. The only difference is that in this case you know who's sending it. Adam Boettiger, of HackingSpam.com has written a short book, 10 Quick Steps to Stopping Spam with several techniques that are not only useful for cutting down on the flow of spam, but can also be extended or altered to deal with the situation we're discussing here.

Instant messaging programs have similar issues, but have simple solutions. MSN messenger, Yahoo Instant Messenger and AOL Instant Messenger all allow you to specify that you'll only allow incoming messages from certain people or allow you to specifically block certain people. Check the Options, or Privacy Settings in the instant messaging client.