Hello,

In the 6.0.0 version new subscribers are NOT ACTIVATED directly (as it should be).
This is due to the default 'state' of table '__jma_subscribers'
This is now '0'. It should be '1'.

Solution:
Added a 6.0.0.sql to components\com_jmailalerts\com_jmailalerts\administrator\sql\updates
with content:
ALTER TABLE `#__jma_subscribers` CHANGE `state` `state` tinyint(1) NOT NULL DEFAULT '1';

Regards,
Peter