It's a bit strange they sent the letter to wikifi-admin@lists.wikimedia.org, which is not a legal entity and doesn't own the website or conduct fundraising for it. It's just a mailing list of Finnish-speaking people who are sysops on the Finnish Wikipedia (not all of them even live in Finland, as there are speakers of Finnish in other countries, also). The organization conducting the fundraising is the Wikimedia Foundation, based in San Francisco, so it would make sense to address the letter to them.