The Kunena team has announce the arrival of Kunena 6.4.7[K 6.4.7] in stable which is now available for download as a native Joomla extension for J! 5.0.x/5.1.x/5.2.x/5.3.x/5.4.x. This version addresses most of the issues that were discovered in K 6.2 / K 6.3 / K 6.4 and issues discovered during the last development stages of K 6.4 Important note: Go to the Kunena Dashboard after an upgrade so that the Kunena database tables are also updated. This is particularly necessary for major version jumps so that the table changes are adapted.
Topics that are moved into this category are generally considered to be closed. Users may want to add additional information but these topics should not be resurrected in order to discuss new problems or unrelated matters.
Kunena is not sending email notifications for new posts any more. It just stopped. Email is working because the other components, are sending notifications.
Kunena uses Joomla mail class to send out the emails -- so if other components work, also Kunena should work. I have no idea why this is not happening to you..
