Maybe I don't explainme well
An undesired mail allways can be sent to any address, but If you can decide to open it or, not delete it or not.
MS Outlook have an script language and that is the security hole, if your mail client let a mail to execute code you can be
exposed to some damage if it is included inside the script, of course if your mail client don't let the mail execute code you are safe and your data,
so, you can see the virus code and learn how where written and nothing happen.

I follow this when I receive an incoming mail
1. Read carefully the message.
2. Check for attachments, file type, who send it, executable or script and so on.
3. Use a web based mail for general pourposes, many of them have an antivirus
4. Don't give my email to all people only to selected people
5. Have separate mail accounts for diferent pourposes
6. Never use Internet Explorer with active controls enabled, never use MSOutlook since all email virus (I think) attack it or inside it.
7. Never forget to do this all time I read an email.

Mauricio