Ban the spam. Reducing the number of strangers who know your address will help minimise the amount of unwanted e-mail you get. When subscribing to a site, don't check off boxes that add your name to online listings - spammers go there to collect addresses. Turn on spam filters at sites that provide them. And if you really want to be cautious, get your free service at a site which lets you specify the senders whose mail you'll accept.
Clear the cache. When you're using a public-access PC to check for e-mail, remember that browsers save information in the system's memory and hard drive when they visit sites. Unless you see (and check off) an increased security option in a public-access PC's log-in screen, you can't assume it will purge pages when you leave - meaning that subsequent users of that computer could read your e-mail. For peace of mind at services that don't offer an explicitly secure log-in, flush the cache manually. (In IE, select Tools-Internet Options-Delete Files. In Navigator, go to Edit-Preferences, expand the Advanced category, click Cache and then clear both the memory and disk caches.) Also, watch what you click. Hotmail, for example, provides two check-in options: one is secure, while the other saves your log-in name and password for instant access. Click the wrong option and you may regret it.
Clear the folders. With Web-based e-mail, the longer you leave messages online, the more time a hacker has to try to read them. Delete messages as soon as you've read them and empty the trash folder. Save messages you'll want to access again to your hard disk. If your service lets you save messages using a regular e-mail program (as both Yahoo and Hotmail do), take advantage of that feature.