[ot] extended posix regexp for email address

[Grovel <40208.nospam@comcast.net>]

Please help, I'm writing C program using <regex.h>.

I need to know the basic or extended posix regexp for a valid email 
address.  I can't use perl regex (don't want the dependency on perl).

I'm guessing it's:

[a-z0-9-+_.]+@[a-z0-9-+_.]+\.[a-z0-9-+_.]+  [with REG_ICASE]