The JSM Mail Handler functionality creates tickets from incoming emails in wrong projects

Issue Summary

When multiple Jira Service Management (JSM) projects are configured with a Mail Handler via Project Settings > Email Requests, the following issue happens:

• the JSM Mail Handler incorrectly maps new incoming emails to the wrong JSM project, instead of the project linked to the mailbox the emails were sent to
• JSM tickets get created in the wrong JSM project

Steps to Reproduce

1. Install Jira Service Management (JSM 4.22.5)
2. Create 2 JSM projects (Project A and Project B)
3. In each project, configure a JSM Mail Handler via the page Project Settings > Email Requests
   • Project A is configured to pull emails from mailbox A
     
   • Project B is configured to pull emails from mailbox B
     
4. Send 2 emails to Mailbox A, and 2 emails to Mailbox B
5. Wait for 5min to give time to the mail handlers to process the incoming emails from their respective mailboxes

Expected Results

The new incoming emails should lead to the creation of JSM tickets in the projects that are mapped to the mailbox they were sent to. In other words:

• The emails sent to Mailbox A will be processed by Project A, and will create JSM tickets in Project A
• The emails sent to Mailbox B will be processed by Project B, and will create JSM tickets in Project B

Actual Results

JSM tickets are created in random/wrong JSM projects.

Using the configuration from the steps to replicate section, if we go to the page ⚙ > Applications > Email Requests, we can see that:

• If we go to the Processing logs of the Mail Handler from Project A, all the 4 incoming emails were processed by that project:
  
• If we go to the Processing logs of the Mail Handler from Project B, no incoming email was process by that project

Notes about the impacted version

The bug is replicable on JSM 4.22.5, but not replicable on JSM 5.0.0 and other LTS versions 4.13.x, 4.20.x.

Workaround

Downgrade "jira-email-processor-plugin" to the previous version:

1. Stop all the Jira nodes in the Data Center Cluster
2. In each Jira node:
   1. Take a backup of the file JIRA_HOME/plugins/installed-plugins/jira-email-processor-plugin-4.22.5-REL-0003.jar and remove it from this folder
   2. Copy the attached file jira-email-processor-plugin-4.22.4-REL-0001.jar to JIRA_HOME/plugins/installed-plugins instead
3. Start each Jira node 1 by 1
4. Go to the page ⚙ > Manage Apps > Manage Apps, search for "jira-email-processor-plugin", and make sure that the version 4.22.4 of this add-on is in use