Question No subscription emails after forum merge

I have pre-existing Kunena forum that is fully operational and containing around 20,000 messages and a few hundred users. Everything appears to be working correctly except that subscription emails aren't being sent. I have checked and know the following:

• I have a test (development) site on the same server which is the original of the site that isn't working. Subscription emails work on that site. The Joomla / Kunena / CB versions match. Configuration matches.
• Other Joomla emailing is working. Test message from global config works. Other moderator emails work. CB emails work.
• The forum correctly indicates new posts in the front end and marks posts read when they are.
• User profiles show subscriptions correctly. They can be set and cleared as expected.
• I've checked this: www.kunena.org/forum/k6-0-support-archiv...to-global-moderators . The tables are present and match those shown in the posting.
• Kunena tools report the database clean and indicate no problems at all.

So what's different between the working test site and broken main site? The origin of the website is a migration from a very much earlier Kunena forum running on Joomla 1.5. The test site started from a snapshot of the original forum in the middle of the last year. I migrated the database tables manually because there was no straightforward upgrade path. We used the forum lightly on the test site during the development process, adding messages and categories. Meanwhile the old site continued operating until changeover about a month ago. At that time I took down the old site and merged the database tables containing updates since the snapshot with the test site tables. Basically I was just added the new messages that had arriving during the interval between starting the test site development and rolling out the new site. Of course, that involved a certain amount of re-indexing messages in the database because different messages had been created in both places, the test site and the old site, during the development process. There's potential for error in that process, but I reiterate that the forum is displaying and working correctly in every respect other than a lack of subscription emails.

Given what I've described, what are the potential reasons that subscription emails might not be sent, what else should I check and how can I debug this please?

Kunena 6.3.10
Joomla 5.2.5 

After some things have been manually imported into the database, it is possible that not everything is synchronized.
1. go to Kunena -> Tools, recount the statistics and synchronize the users.
2. log in to the frontend with a test user (this user must have a valid email address) and subscribe to a topic or category
3. log out this test user
4. log in with another user and reply to this subscribed topic
5. check whether the test user receives an e-mail
 

@rich very interesting!

I have previously run tools>recount statistics, but I did it again anyway. I then synchronised users as you said. That reported that it did nothing.


I followed steps 2 to 5, posting with a test account created on the new site recently (not imported). The test account did receive a subscription email from Kunena ("a new reply has been posted ..."). Good news! So I logged back in as the test account and responded further on the same thread expecting to receive a similar subscription email to my own account, now indicated as subscribed to the topic. No email received. I went back to my account and responded again. Further email received to the test account.

So I think we've proven (a) that Kunena can send subscription email and (b) that it will do so to a new(ish) account. There appears to be a problem with sending subscription emails to pre-existing user accounts, at least some of them and possibly all. I guess this must therefore be a database anomaly of some sort. Can you suggest where I need to look or what that might be please?

Have you checked user profile from users that don't receive notifications?
 

I noticed in #__kunena_users the test account and all other new accounts, those created by the new site, not imported, had the banned field set to 1000-01-01 00:00:00 whilst all the pre-existing accounts had this set to NULL. I changed this field on my own account to match the test account and then went back to the forum with the test account to again reply on the test thread. That successfully caused a subscription email to be sent to my personal account! So I've run this update on all user accounts and await further feedback.

UPDATE `#__kunena_users` SET `banned` = "1000-01-01 00:00:00" WHERE `banned` is NULL

It looks like the NULL values in #__kunena_users banned field are preventing subscription emails being sent. Note that #__kunena_users_banned is an empty table, ie. nobody is or ever has been banned. Perhaps this is an unusual situation, but it seems like undesirable sensitivity.

@Pinkeltje these are my account settings. Looks like it takes the forum default which is set to "yes" in the forum configuration. I see plenty of evidence that I'm subscribed to both topics and categories.