This is a peer user support forum for Thunderbird.

If you have questions about the donation requirements I suggest you use the contact us links in the donation process. It takes you here https://www.thunderbird.net/en-US/donate/help/

There are requirements placed by finance providers and by assorted governments around the world that the donation process must accommodate. The best I can do is point you to the donations FAQ https://www.thunderbird.net/en-US/donate/#faq where they say.

Why do you need my address in order to process a gift? We understand that your privacy is very important. We ask for a minimum amount of information required to process credit card payments, including billing addresses. This allows our payment processor to verify your identity, process your payment, and prevent fraudulent charges to your credit card. We keep your information private — if you have questions, please refer to our Privacy Policy. If you would rather not fill in your information on our online form, you can mail us a check.

Why is paypal's verification (which is checked through my bank) not enough?

Under FAQ it says: This allows our payment processor to verify your identity, process your payment, and prevent fraudulent charges to your credit card.

I am not paying by credit card, but by PayPal (as is the author of this post), so this doesn't explain why it is necessary.

I cannot contact the donations contact as the 'submit' button in 'contact us' of 'donate' doesnt work.