The quickest way to get in contact is usually the options shown on the drawpile.net help page. Especially for general questions or suggestions, that is probably the best avenue, since there's many people in those channels from different countries that may be able to assist and weigh in. Don't write your private information into the public channels obviously.
If you want to get in contact directly, please send an e-mail to
donations@drawpile.org. Please also don't write private
information into your initial message, we'd rather confirm that we actually
need that personal data first.