if ($opt{'c'}) {
 open CATLOG, "<$MAILLOG";
 while (my $line = <CATLOG>) { while_sub($line); }
} else {
 $log = File::Tail->new( name => $MAILLOG, tail => -1);
 while (defined(my $line=$log->read)) { while_sub($line); }
}

##</code><code>##

if ($opt{'c'}) {
 open CATLOG, "<$MAILLOG";
 while (my $line = <CATLOG>) {
} else {
 $log = File::Tail->new( name => $MAILLOG, tail => -1);
 while (defined(my $line=$log->read)) {
}
 ...while loop code here...
 } # End while loop
close (CATLOG) if ($opt{'c'});

##</code><code>##

 if ($opt{'c'}) {
   open MAILLOG_R, "<$MAILLOG"
     or die("Unable to open mail log: $!\n");
 } else {
   tie *MAILLOG_R, 'File::Tail', (name => $MAILLOG, tail => -1);
 }

 while(my $line = <MAILLOG_R>) {
  ...blah...
 }