my @ar = (); # empty array
while(<>){
   #for every match in the line 
   #(if there are more than one email in a line)
   while(/<a href="(mailto:)?([^"]*)">([^<]*)<\/a>/g){ 
      push @ar, "$3\t$2";
   }
}
open ...
for(sort @ar){
   my ($name, $email) = split/\t/;
   print OUT qq(<a href="mailto:$email">$name</a><br />\n);
}