I want to make a form to earn yearly repeated donations. I want to prevent abuse so I'd like to send an automated mail to people subscribing. Asking them to click a link to prove they are really who they say they are. Is anybody aware of a xoops module doing this job?

Can't you use profile module with a checkbox field? The register process would take care of it.

Thanks for the idea Trabis, but this solution is way to complicated for the site in question. I don't use the user section at all and see no use enabling it, registering with name and password doesn't make sense when only telling you want to donate on a yearly basis.

A module like liaise is what I am looking for, but it lacks an email check. Evennews has the email check but cannot be expanded with extra checkboxes or fields...

I don't understand the idea. Maybe you could explain step by step.

You want to give or receive donations?
You want to prevent abuse as if you don't want to receive donations from strangers?
Why do you need the email, is not captcha enough?

Can you give me an example on how you plan to use liaise? What fields will you be requesting?

Is this what you want? :
-User click a link to subscription form.
-User gets a form that asks for email address (not the subscription form)
-User gets a message saying "a confirmation email as been sent to your email"
-User clicks on the email link
-Liaise confirms user email is valid and give him access to the subscription form.
-User submits the form and admin gets the email with the form data.

Btw, you could create a subscription service using Paypal and provide your visitors a link to the paypal page.