my $username = "bob";
my $datafile = '/etc/postfix/virtual' ;
my $req_addr = "$username\@test1.com" ;

#Edit Postfix Virtual File

my ( $name, $domain ) = $req_addr =~ /^([\w.-]+)(@[\w.-]+)$/ ;
open FH, $datafile or die "Couldn't read $datafile: $!" ;
my @virtual = <FH> ;
close FH ;
open FH, ">$datafile" or die "Couldn't write $datafile: $!" ;
my $wrote_it = 0 ;
  for ( @virtual )
  {
    print FH $_ ;
    if ( $_ =~ /test1.com/ && !$wrote_it )
    {
            print FH "$req_addr\t$username\n" ;
      $wrote_it++ ;
    }
  }  
close FH ;