[UA-discuss] [UA-EAI] Regular Expression To Validate EAI Addresses

[Arnt Gulbrandsen]

Writing a single regexp is probably forbiddingly complicated (and I say 
that as someone who once wrote a 25-line regexp and used it in 
production), but writing two might work well.

One that accepts most 
valid names and accepts noting invalid, and one that rejects 
common/assumedly common errors and accepts everything that's valid (and 
some errors). These should be simple to write, and yield three answers: 
good, bad and uncertain.

Arnt