1-2-All can save the info about mailing in a log table. In order to turn this feature on, please define a variable in your engine.inc.php file:
$GLOBALS['log_mailing'] = 1;
Then you can find the logs on what happened with what email address in database table 12all_logs.
Mailings are those with responder field set to 0 and message field to mailing ID.
Comment field has been added in version 4.62.1 which holds the debugging info for that subscriber. It works only for mailings and logs according to sending engine's logging level.
