we've issues the 421 response, so just exit now -- nothing good will come of this
reject octets that are out of range
octets with leading zeros: strange, but I guess acceptable
Octets with leading zeros: strange, but I guess acceptable.

Why not >2 leading zeros?
small improvements
switch from boost::regex to std::regex
GCC 4.9 required now for std::regex
Merge branch 'ugly_ugly_regex' of github.com:gene-hightower/ghsmtp into ugly_ugly_regex

I might be getting the hang of this work flow.