3Com Professional Handbook To define filter strings:

Chapter 1: Mail page 29
implicit OR; because of this, you should not enter connecting
words, such as AND or OR.
To create a more complex filter, you can define filter strings for
the To, From, and Subject fields simultaneously. Your PalmPilot
joins the filter strings for these fields using an implicit AND. Once
again, you should not add connecting words. Your PalmPilot will
do that for you.
For example, suppose you want to receive only messages from
John Smith (jsmith@aol.com) or Jack Jones (jjones@aol.com)
concerning the Apollo Project. You would create the following
filter strings:
To filter string: jsmith@aol.com, jjones@aol.com
Subject filter string: Apollo Project
Your PalmPilot interprets this as, “Accept messages about the
Apollo Project from John Smith or Jack Jones. Do not accept
messages from other people. Do not accept messages from John
or Jack about any other subject.”
When you define a string, note that your PalmPilot will search for
any instance of that collection of characters. For example, if you
create a filter where only messages containing the string “info” are
retrieved, PalmPilot considers “info,” “rainforest,” and “kinfolk,”
appropriate matches.
To define filter strings:
1. In the HotSync Options dialog, tap the line that corresponds to
a specific header field. A cursor appears at the beginning of
that line, representing the point where new text will appear, as
shown in the following diagram: