Well I am getting some tutorials now and trying to parse your previous example ( go easy on me tho :). From the beginning I`ve started with something simple as that (using a simple divide and conquer technique) :

my $match;
if ( $match = split(/\s/, 'somemail@yahu.com') == 1 ) {
  # do we have a whole string with no spaces in it?
  # if so check for '@'
  if ( $match = split("@", 'somemail@yahu.com') == 2 ) {
         # if it`s split by 2 then it must be 1 @ sign
         # then do some other nested checks 
         # whith regex for validating mail ex. are there any 
         # dots or hash signs in the end of domain etc.
      }
}
else {
    print "Mail verification form failed!\n";
    # call back the mail form
 }
[download]

Now I`ll keep going with regex to master it because I really want to know what is going on there and how.