https://technet.microsoft.com/en-us/library/jj200769%28v=exchg.150%29.aspx is useless. If you want to spam with no action whatsoever from the 800 pound gorilla of email, who are also too large to be added to any blocklists anywhere, sign up with Office 365 and there you go.
Recent player: Markkinointirekisteri.fi, Finnish vendor of spam lists going back at least six years.
Growmail.co.uk will probably have reason to take a look at hulabaloo.net / huippudiili.net (two anonymized domains sending materials in Finnish) now that asuntojenmyynti.fi used their services to spam. It would be interesting to see the contents of the FI-LISTA.
Snakker du dansk, Ville? Oh, but you don’t need to, ‘cuz your Danish collaborator is a guy from Helsinki.