The blog of Ross Fruen, a .NET consultant

reCAPTCHA and nms FormMail - part I

Another site I manage uses nms FormMail to provide visitors with a way to get in contact.

To help reduce spam encountered by this site a reCAPTCHA challenge has been added to the form used by FormMail.

This post, together with the second in the series, discuss the changes required to add reCAPTCHA to nmsFormMail.

To achieve this the following changes were made to the nms FormMail script...

At the beginning of the script reference the light weight user agent LWP::UserAgent...


use strict;
use vars qw(
$DEBUGGING $emulate_matts_code $secure %more_config
$allow_empty_ref $max_recipients $mailprog @referers
@allow_mail_to @recipients %recipient_alias
@valid_ENV $date_fmt $style $send_confirmation_mail
$confirmation_text $locale $charset $no_content
$double_spacing $wrap_text $wrap_style $postmaster
use LWP::UserAgent;

In the handle_request() method add a call to check_captcha after checking for missing fields.

my @missing = $self->get_missing_fields;
if (scalar @missing) {

$self->check_captcha or return;

my $date = $self->date_string;

After check_method_is_post() insert the sub routine check_captcha()... Not forgetting to replace 'your_private_key' with your private key.

=item check_captcha ()

Check the CAPTCHA response via the reCAPTCHA service.


sub check_captcha {

my ($self) = @_;
my ($ua) = LWP::UserAgent->new();
my ($result) = ($ua)->post(
privatekey => 'your_private_key',
remoteip => $ENV{'REMOTE_ADDR'},
challenge => $self->{Form}{'recaptcha_challenge_field'},
response => $self->{Form}{'recaptcha_response_field'}

if ( $result->is_success && $result->content =~ /^true/) {
return 1;
} else {

if ($self->{FormConfig}{'captcha_fail_redirect'}) {
print $self->cgi_object->redirect( $self->{FormConfig}{'captcha_fail_redirect'} );

return 0;
else {
my ($self) = @_;
$self->error_page( 'Error: Captcha Check Failed', <<END );
The Captcha response of the form you submitted did not match the challenge.
Please check the form and make sure that your response matches the challenge in the captcha image.
You can use the browser back button to return to the form.
return 0;

Add an additional form field captcha_fail_redirect to configuration_form_fields



And finally add captcha_fail_redirect to the list of valid names in parse_config_form_input

my $val = $self->strip_nonprint($self->cgi_object->param($name));
if ($name =~ /return_link_url|redirect|captcha_fail_redirect$/) {
$val = $self->validate_url($val);
$self->{FormConfig}{$name} = $val;

A modified nms FormMail script is available for download.


  1. Thanks for this information, I was not sure I was going to be able to get this to work for me but your instructions worked like a charm.

    - Written on 23rd November 2010 by SN
  2. Thank you so much!! I have been fighting with adding a captcha to our contact form for a week now. Nothing worked until I found yours. Thanks again!!


    A Touch of Ozark

    - Written on 6th November 2012 by Steve

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