Create a simple regex line on Zencart to prevent bots and spammers to Sign In

I have a webstore running on Zen Cart version 1.5.0. Recently I have dozens of fake customers registering on my store and I want to prevent these bots and spammers from creating new accounts. I don't want to include any Captcha solutions, I just need one or two regex lines on the PHP to prevent Post Codes longer than 10 characters and Names over 12 characters on the "New Account" creation.