I have a client who has been using WooCommerce for a while with no problems, but a few updates ago (I think around 2.4.4), new order emails suddenly stopped sending.
- All other order emails and site emails were sending
- I verified that New Order emails were still enabled under WooCommerce > Settings > Emails
- I tried changing the emails to multipart or text only
- WordPress core and all plugins were updated
- I had not made any other changes (besides updates) to the site
- I verified that new orders were still coming in as “Processing”
Plugin author Mike Jolley suggested that I try https://wordpress.org/plugins/wp-mail-smtp/. I hesitated because all the other emails were sending and I didn’t think this email was any more content heavy than the others, but I decided to give it a try.
Success! New order emails are now sending again!