Every address here says where it came from. 9 of 19 come straight from the provider's own pages; the rest from directories or user reports, and we mark which is which. For 2 we're still not certain which company you're actually contracting with, and we say so rather than guess.
Primary means the provider said it themselves, in their Impressum, terms, cancellation page or invoice footer. Telekom's postal address is primary because it's printed at the bottom of every Telekom invoice.
Secondary means an established directory. Usable, but send by registered mail so you've got proof of delivery.
Community means somebody posted it in a support forum. We show it because it's often all there is, and we never use it for automated sending.
A letter to the company's registered office still reaches the company. Under § 130 BGB a declaration takes effect once it enters the recipient's sphere of control, whatever department they'd have preferred. So a missing cancellation address means a slower route, not a dead end.
The exception is where sources disagree about which company you're contracting with. There we won't produce a letter at all, because sending a cancellation to the wrong company is worse than admitting we don't know.
We've verified addresses and rules for 19 German providers so far. If yours isn't one of them, tell us and we'll add it, usually the same day.
Tell us the name and we'll research it properly — Impressum first, then their own cancellation page, then directories, and add it with its source shown, same as everything else here.
This directory is free and needs no account. If you'd rather write your own letter and post it yourself, everything you need is right here. We'd rather be useful than hide an address behind a payment.