This 2.1 distribution is the second full-production release, fixing some minor bugs reported in 2.0 and adding a few new features. Here are fetchmail's main features.
Host is auto-probed for a working server if no protocol is specified for the connection.
This means the retrieved mail automatically goes to the system default MDA as if it were normal sender-initiated SMTP mail. Easy control via command line or free-format run control file. This enables replies to work correctly. Strict conformance to relevant RFCs and good debugging options. You could use fetchmail to test and debug server implementatations.