When a text field is being searched (subject, author, address and text), special wild characters can be used to create a more sophisticated search.

% Matches zero or more occurrences of any characters.
_ Matches any single character.

By default each string that you enter, is implicitly surrounded by the percent (%) wild character. This permits you to enter a portion of the field that is being searched and find any item that contains the string that you entered. 

Click on the ? for information about the Advanced Text Search syntax.

There is a limit of 1000 messages that can be retrieved. Enter a more specific search to have all messages returned.