Immediate delivery of held messages after rental agreement signing

Problem: There is currently a delay of up to 30 minutes before scheduled messages (like check-in instructions) are sent after a guest signs a required rental agreement.

Current Workaround: Manually sending the message via the Activity log in the Inbox.

Impact: Reduced efficiency and a potential gap in guest communication during a critical window.

Proposed Solution: Trigger the release of held messages immediately upon the signing of the rental agreement.

Unlock: Guests receive their essential check-in details instantly, improving the guest experience and reducing manual overhead for hosts.