Other programs, like Esys' Simeon, will change the way messages are sorted and displayed within a mail folder. Both methods have advantages and disadvantages, but in the end can be equally effective in helping you organize incoming mail. The concept behind mail filtering is that you use some parameter of the E-mail header to determine where that particular piece of mail will be filed. For example, if you frequently receive mail from a person named Fred, you could filter Fred's mail into a particular folder or group by telling your E-mail program to look for Fred's address as part of the from address. If you wanted your replies to Fred to be placed with the incoming messages, you could tell your E-mail program to look for Fred's address as the destination also.
Filters have a number of uses beyond just identifying mail from individuals.
If you subscribe to E-mail mailing lists, filters can be useful for segregating your mailing list mail from the rest of your mail. If you frequently receive junk E-mail from a particular site or address, you can filter that mail to one location and throw it away with just one operation. Novell's GroupWise implements filters as part of its Rules facility. Consult the GroupWise Help file for more information about setting up a mail filtering rule. A previous version of this column talked about mail filtering in Pegasus Mail and for UNIX-based mail systems.