How do I ask another brokerage for permission to market a listing?

Start with the listing agent. If you do not know them, go to the managing broker at the listing brokerage. Keep the ask short and specific:

1. Name the property by address.
2. Say you want to market it on Facebook Marketplace as the marketing agent.
3. Say the post will credit their brokerage as the listing courtesy of line and will carry the on behalf disclosure.
4. Ask whether their permission covers this one listing or all of their listings.

Save the reply with the listing. A reply by email is enough to keep a clear record. If the answer is no, or you hear nothing, do not post that listing.

Wording and terms are between you and the other brokerage. Your broker can tell you what your office requires.