If you use Google's Gmail as your email program of choice -- as I do -- then you'll want to read the following article for many useful tips: Note: Ignore the drop down box asking for a login. Click on "Continue reading" to read the entire article.
http://www.minterest.org/gmail-tips-and-tricks/#customize
There are many attributes I enjoy about Gmail, but one that I really appreciate and use often is the 'search' function. If, for example, you sent an email to, say, 'Joe' or 'Jane' about 3 or 6 or ? months ago and need to retrieve some info from that email, just use the search function.
Jim Hamm