Currently, when a message is delivered, a watchlist entry corresponding to the skipped delivery log entry is generated for pages which have opted out of MassMessage delivery. This shouldn't happen, since people who have opted out probably don't want to know about deliveries at all.
Version: master
Severity: normal
URL: https://www.mediawiki.org/wiki/Thread:Extension_talk:MassMessage/Mass_Message_Log
@wctaiwan If this is still relevant, the log entry is created by the function below. If the third parameter (the target) was changed so that it was no longer tied to the page, it would also be harder to track users who opted out and to move the log entries following renames, page moves, etc. I'm not sure that removing this is a good idea.
protected function logLocalSkip( $reason ) {
$logEntry = new ManualLogEntry( 'massmessage', $reason );
$logEntry->setPerformer( $this->getUser() );
$logEntry->setTarget( $this->title );
$logEntry->setParameters( [
'4::subject' => $this->params['subject']
] );
$logid = $logEntry->insert();
$logEntry->publish( $logid );
}