WP mail sent to MS Exchange recipients = occasional email corruption?
I run into the same issue and after a research, I found out that this is a bug with class-phpmailer.php. The bug was apparently introduced in WP 4.3.2. Even if the changelog doesn’t mention it, the file was modified. Only reverting wp-includes/class-phpmailer.php to the version that was included in WP 4.3.1 fixed the issue. The … Read more