Contact
One address, read by a person. There is no ticket system and no chatbot in front of it.
Support
Something not working, a figure that looks wrong, or a question about how a settlement was reached — write in and describe what you expected and what you saw. If it is about a specific month, saying which mess and which month gets you a useful answer faster.
Deleting your account
You can do this yourself: the Delete account button is at the bottom of the More page, in the app and on the web. No need to write in. The privacy policy explains exactly what is removed and what stays in your mess's shared record.
Security
If you have found a vulnerability, please tell us before telling anyone else, and give us a reasonable chance to fix it. Reports are welcome and taken seriously.
Anything else
Feature requests, a mess with an arrangement the app cannot express yet, or a language you would like it to speak — all worth writing about. The product has been shaped by how messes actually work rather than by a plan made in advance.