Hello,
We are running WP4.42 multisite network and WP Better Emails has always worked perfectly for us on all subsites and with all other plugins we have ever tested. In fact, we run over 300 plugins at the same time as WP Better Emails without issue, so it seems to get along fine with everything.
However, upon switching from Mandrill to SendGrid we encountered the same issue as reported. All emails get send as plain text.
We have SendGrid configured for API access.
Site emails that send perfectly formatted in HTML when SendGrid is not active get stripped down to text only when SendGrid is activated.
I have tried configuring SendGrid without entering a SendGrid Email Template ID and also with entering a SendGrid email Template Id. When a SendGrid Email Template ID is entered, the emails are delivered using that SendGrid template, so it appears that the SendGrid plugin is somehow intercepting and overriding all email templating of other plugins – including WP Better Emails.
We have reported this issue to SendGrid as it seems to be related to their plugin; however, I thought you would want to know since many people may be switching to SendGrid within the next 30-45 days because Mandril is discontinuing their stand alone service. As a result this issue is likely to be reported a lot in the next month.
Debug bar does not report any issues and the debug log does not seem to provide any clues either.
I can provide access credentials to a test site on our network, if you want to explore what may be happening.
Any assistance will be appreciated.
Thank you!