use strict;
           use CGI;

           #use some mail module like MIME::Lite 

           open(Filenm,"filenames.csv") || die "the file is not ready to be opened";

           while (<Filenm>){

              local $/;
              # Here the file's size is important, for a lesser size this is ok

              my @pindigits = split(',',$_);
              $pinforphonecard = shift(@pindigits);

              #    have the cgi stuff and MIME::Lite or any that you use for mailing part with the $pinforphonecard as the one to be let to send 

              # then go ahead and remove the $pinforphonecard and a comma from the file 

              $_ =~ s/$pinforphonecard,//g;
              last;

            }