Issue Summary

When using the system's "Send email" feature and selecting project roles or groups that result in emails being sent to a large number of users, admins may encounter a 504 Gateway Timeout error. This happens when the system fails to send a response in time due to the volume of emails being processed, and the browser displays the error message:

Steps to Reproduce

1. Create or use a group containing a large number of users (e.g., 10,000+).
2. Navigate to the system's "Send emails" page.
3. Select the group with all users in the "To" field.
4. Attempt to send the email and wait for the response.

Expected Results

If the email list is too large, the system should notify the user that the emails are being processed and results will be sent later, rather than attempting to display a full response that leads to a timeout error.

Actual Results

The admin receives a 504 Gateway Timeout error in the browser due to the system's inability to handle the large volume of emails in time.

Workaround

Currently, there is no known workaround for this behavior. A workaround will be added here when available.