This is related to the fix on cross commenting in https://jira.atlassian.com/browse/JSDSERVER-4246

• Before 3.2.0, users can cross comment. When users sends an email to the email channel configured in project A with a subject containing the issue key of project B, JIRA will add this email as a comment to the issue in project B.
• From 3.2.0 to 3.2.5, users can no longer cross comment. SD creates a new issue in project B instead.
• From 3.2.6 to 4.18.0, users can cross comment again due to the fix in https://jira.atlassian.com/browse/JSDSERVER-4246
• From 4.18.1 to 4.18.2, users can no longer cross comment due to the fix in https://jira.atlassian.com/browse/JSDSERVER-6511
• 4.19.0 onwards, users can cross comment again since the fix https://jira.atlassian.com/browse/JSDSERVER-6511 was removed in 4.19.0

Some users have expressed that the behavior in 3.2.0 - 3.2.5 is preferred, the reasoning is that if they are sending an email to project A's mailbox, it means they want to have the issue created in project A.

However, some users have expressed that the behavior in 3.2.6 - 4.17.x is preferred, meaning that is an email is set to Project A's mailbox and contains a reference to an issue from Project B, they want the mail handler to add a comment to the issue from Project B, rather than creating a new issue in Project A.

There should be an option to allow users to switch between the two behaviors, to better suit their organization's use case.