Reply Message Board post in "root" category by email doesn't notify subscribers

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 6.2.X EE, 7.0.0 M5
• Fix Version/s: 6.2.4 CE GA5, 6.2.X EE, 7.0.0 M5
• Component/s: Mail, Message Boards, User Notifications, ~ [Archived] Collaboration
• Labels:
  • ee-ts
  • liferay-fixpack-portal-55-6210
• Branch Version/s:
  6.2.x
• Backported to Branch:
  Committed
• Story Points: 24
• Fix Priority: 4
• Git Pull Request: https://github.com/sergiogonzalez/liferay-portal/pull/2003

Issue
If the thread is created under the root of Message Boards, users will not get notified by email when one user replies the thread via email. This issue does not exist when the thread is under subcategory of Message Boards.

Reproduction Steps
1. Include the following in portal-ext properties
pop.server.notifications.enabled=true
pop.server.notifications.interval=1
pop.server.subdomain=
2. Access Liferay portal using a test domain (abc.test.com)
3. Start up portal and configure Control Panel>Server Admin>Mail to send/receive email
Mail Details: (You can use Gmail but need VPN)
pop.163.com / 110
smtp.163.com / 25
Enter personal 163 account and password as a email server

(In the personal 163 account, in Settings > mail settings > POP3/SMTP/IMAP, enable POP3 service. Need text message verification.
Note: the service will delete the notification message as soon as Liferay
retrieve it and posted to MB. But all of your messages in the Inbox will be
deleted and backup by 163 mail)
4. In Portal Settings,
set Virtual Host to abc.test.com.
change mail domain to 163.com
In Configuration > Email Notifications --> Sender, set the email address as the personal 163 account

5. Add Message Board portlet on the page, in Configuration > Email From > Address, enter the email address the same as the personal 163 account. (If you already set it in portal settings above, here the information will be updated accordingly)
6. Create User A and User B and assign Site Membership to the site
7. Login as User A and User B separately to subscribe the MB
8. Create a category as Admin and post a new thread in the category
Result: Both User A and User B will receive the notification email.
9. User A reply the thread via email
Result: The message is posted on MB. Both User A and User B will get the notification email.
10. Directly post a new thread under the root of MB as Admin
Result: Both User A and User B will receive the notification email.
11. User A reply the thread via email

Expected Result:: Both User A and User B get Notification email.

Actual Result: The message is posted on MB, however, neither User A nor User B will receive the notification email.