That has become a known issue... (Support requests)
Please check the post below:
http://www.lavasoftworks.com/smtping/forum/index.php?id=18
I've put there instructions on how to deal with it :)
Complete thread:
- Error message. - Don Cook, 2013-03-26, 21:52
- That has become a known issue... - acaballero, 2013-03-26, 23:05