In a two-sided marketplace, there are different communication methods that can be used, depending on the platform's business model and goals. However, the most common method is to have the platform handle the communication between the two parties.

In the case of a B2B commercial real estate platform where commercial spaces can upload their listings, it would make sense for the platform to handle whatever messages the listings receive and forward them or notify the respective companies who listed on the platform. This approach ensures that the platform can monitor and moderate the communication to maintain a high level of professionalism and prevent any inappropriate behavior.

By having the platform manage the communication, it also ensures that all parties are using the same communication channel, which makes it easier for the platform to track communications and monitor performance. Additionally, it helps to reduce the risk of spam or unwanted messages, as the platform can filter and moderate the messages.

Overall, having the platform handle the communication between parties is the standard protocol for two-sided marketplaces. It helps to streamline the process, ensure quality control, and provide a better experience for all parties involved.