Simple to implement, these tips can be a good start to making sure your e-mail communication becomes more secure.
1. Understand that no e-mail communication is 100% secure. We can do our best to make the percentage close to that, but sometimes - if the information is extremely important - you should consider ditching the e-mail option and deliver it in person (if possible). Avoid sending credit card or social security numbers via e-mail. It's also a good idea not to send user names and passwords for accounts you don't want to see compromised.
2. The more your e-mail is present in the confines of the cyberworld, the more spam you'll be likely to receive. Unfortunately, even if you're careful with disclosing your e-mail, chances are people will include you in mass mailings and you eventually your e-mail will be out there. To counteract this, you should definitely set up filters and rules. They will not catch every unwanted e-mail, but they will reduce their number. This is not just a matter of annoyance - basic users and novices are more susceptible to spam and scams. So why give the bad guys the possibility of trying out their angle?
3. Tied to the previous advice is this one: choose plain text over full HTML or XHTML rendition to reduce the risk of being targeted by a phishing attack.
4. Don't open attachments unless you know who it's coming from and you trust them.
5. Use encryption. Check with your ISP to see if they encrypt the authentication process. Encrypt your email message if possible. Are you familiar with the concept of steganography? You can hide messages in images, articles, shopping lists... Ideally, you can use both - first encrypt the message, then use a steganography software to embed it in a recent photograph. There are simple tools out there.
6. Don't access your e-mail from an unsecured network or potentially compromised computers. Yes, that particularly includes access from an Internet cafe. There be keyloggers.
7. Teach everybody who wants to know about it, especially your children (AND especially if you're using the same computer).
Courtesy : www.net-security.org