VPOP3 supports DOS-style wildcards in many places of the configuration. You may be familiar with DOS wildcards (they are used in Windows & Linux as well, but most people know them from the days of MSDOS, so we call them DOS-style wildcards), but, if not, the following should help.
The wildcards supported by VPOP3 are:
* - this matches any sequence of characters, including an empty sequence
? - this matches any single character (but not a missing character)
Wildcard comparisons are 'anchored' at start and end, and they are performed in a case insensitive manner.
So, given the word "abracadabra":
ocad will not match
o*cad* will match
oabra* will match
o*abra will match
oabracadabra* will match
oabra*abra will match
oabra???abra will match
oabracadabr? will match
oabracadabra? will not match
If you need more flexible text comparisons, then look at Regular Expressions in the next section.