In VPOP3 6.8 SSL v2 is disabled by default (it is considered to be insecure). SSL v3 was released in 1996 and SSL v2 was deprecated because of the well known security flaws.
However, it seems that Microsoft Outlook (up to at least Outlook 2010) will not connect to VPOP3 using SSL if VPOP3's SSL v2 is disabled.
So, to use Outlook with VPOP3 with SSL/TLS you may need to re-enable the SSL v2 support in VPOP3. To do this, in the VPOP3 settings, go to Services → General, and go to the SSL Settings tab. Turn on the Allow SSL v2 setting, Submit the change, and restart VPOP3.
(Note that this change may cause problems if your business has to meet certain security requirements - in this case you may need to use a more secure email client or talk to your Microsoft technical support contact).