After the upgrade, I noticed I was having problems with email notifications when comments are posted. Basically, there are no emails being sent. Whereas prior to the upgrade, email notifications for posted comments were working fine.
I performed a diff between the versions of the files wp-include/pluggable.php and found that the only different is that the new version excluded the following line:
$phpmailer->Sender = apply_filters( ‘wp_mail_from’, $from_email );
I understand that others have had problems when this line was included in previous versions, but my problem is quite the opposite. So, if you may be suffering from lack of emails when people post comments, you may wish to include this line back in (or just revert your copy of wp-include/pluggable.php).
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