my $req_addr = 'bob@domain1.com';
my ( $name, $domain ) = $req_addr =~ /^([\w.-]+)(@[\w.-]+)$/ ;
open FH, $datafile or die "Could Not Read Virtual File" ;
my @virtual = <FH> ;
close FH ;
open FH, ">$datafile" or die "Could Not Write Virtual File" ;
my $wrote_it = 0 ;
  for ( @virtual )
  {
    print FH $_ ;
    if ( $_ =~ /domain1.com/ && !$wrote_it )
    {
            print FH "$req_addr\t$username\n" ;
      $wrote_it++ ;
    }
  }  
close FH ;

my $req_addr = 'bob@domain2.com';
my ( $name, $domain ) = $req_addr =~ /^([\w.-]+)(@[\w.-]+)$/ ;
open FH, $datafile or die "Could Not Read Virtual File" ;
my @virtual = <FH> ;
close FH ;
open FH, ">$datafile" or die "Could Not Write Virtual File" ;
my $wrote_it = 0 ;
  for ( @virtual )
  {
    print FH $_ ;
    if ( $_ =~ /domain2.com/ && !$wrote_it )
    {
            print FH "$req_addr\t$username\n" ;
      $wrote_it++ ;
    }
  }  
close FH ;