Checkbox checked from an email

[ryanzroost]

I am trying to auto-populate a web form from a link in an email using module_url.  I can populate input fields just fine but I am trying to also get a checkbox to be selected by default. 

Anyone know how this can be accomplished through a link in an email?

[Liam Dilley]

You have to do this with javascript. If url parameter exists (fort that specific one) then checked="checked"