If you are getting unwanted spam submissions in your website, it means spam robots are posting information on your forms.
To stop this, you must activate Captcha (image verification) on your forms.
Go to your back office [domain]/admin
Customize Website > Customize Website Info
Uncheck “Hide image verification (Captcha) in your forms?”
All your system forms will then have image verification.
For Custom Forms, you must enable image verification for each form. To do this, go to
“Customize Website” > “Create Custom Forms“, edit the form you want to edit, and enable captcha.
Similarly, you should never post your email address on your website. Sooner or later it gets picked up by spam robots, and you will be receiving more spam email than you can handle.