Reject Form Submissions with URL in them I have a client who is using Drupal and has an email contact form.  The problem is they are getting spam sent through the form daily.

I have tried the Re-captcha plugin, captcha plugin, Anti-spam (Askimat), and Honeypot plugins.

The offenders are using programs like XRumer which is capable of solving captcha's and none of these plugins have been able to stop the bots.

So I am asking others if they have any advice on how to stop these contact form spam submissions?

Since this particular form shouldn't have a legitimate reason for a URL in the body section, possibly I could detect URL's and then return an error if they are present when a form is submitted?
It is possible to create contact forms using either the Webform module, or the Entityforms module. 

The beauty of the latter is the ability to attach fields, and to validate those fields with the Field Validation module, which offers a wide range of validation options.

There is a Webform Validation module for use with Webforms, but I think you will find Entityforms with Field validation to be a little more flexible and, perhaps, easier to use.

Either one should let you scan text for say "&lt;a href=" or any other undesireable word or phrase (blacklist matching) or constructs using regular expressions, if you are so inclined.