This feature request proposes enhancing Jira Service Desk with more granular security controls based on customer organization domains. Specifically, we request the ability to restrict which organizations can view and comment on specific tickets, using email domain validation as a key security measure.
Organizations using Jira Service Desk to support multiple clients currently face security challenges when managing all clients through a centralized service desk. While the Organizations feature provides some grouping capabilities, it lacks sufficient permission controls to ensure proper isolation between different client organizations.
We request the ability to configure permissions that restrict which organizations can interact with specific tickets via Email based on their associated email domains. This would prevent users from one organization from accidentally or deliberately adding sensitive data to tickets belonging to another organization.

The solution we think could be valuable is Enhanced Email Validation rules that can be enabled for Service Desks utilizing the "Organizations" feature. 

The system should validate incoming emails against organization domains and enforce appropriate access restrictions. When an email is received, Jira should:

1. Identify the sender's domain
2. Associate it with the correct organization
3. Apply appropriate permissions based on organization access rules configured by the project's administrators.
4. Reject email interactions if the sender doesn't have appropriate permissions.

Another critical security enhancement could be protection against "key collisions" where external Jira instances from customers might use identical project keys. If they forward emails which include metadata from their Jira instance, the system should have safeguards to prevent external users from commenting on tickets by including project keys in email subjects, particularly when those users belong to organizations that should not have access to those tickets or some other metadata is included to prevent commenting.

Benefits of these adjustments would include:

• Improved data privacy and security between different client organizations
• Reduced risk of accidental information disclosure
• Enhanced compliance with data protection regulations
• Ability to safely maintain a centralized service desk for multiple clients
• Prevention of potential abuse through email-based ticket manipulation

The most likely use case for this feature would be a service provider supports multiple clients through a single Jira Service Desk instance. The provider wants to ensure that when Client A sends an email to comment on a ticket, they cannot accidentally or deliberately view or modify tickets or email history (comments) belonging to Client B, even if they reference the same ticket key.

This feature would allow service providers to leverage the efficiency of a centralized service desk while maintaining proper security boundaries between different client organizations.