I can't help you with your problem directly (what's the error message? What's in $FORM{'email'} ?). But one of the most common advices about DBI stuff is to use placeholders. I'd write that piece code in this way:

my $sth = $dbh->prepare( qq|
  select count( * ) 
  from 
    userlist
  where
    colemail = ?
|) || die $dbh->errstr;

$sth->execute( $FORM{'email'} );
[download]

Michael G. Schwern has several good points here: http://magnonel.guild.net/~schwern/talks/Refactoring_DBI_Example/