I've noticed an issue recently with some HTML emails from a particular sender showing up in Outlook as a blank message with the email components (.html file and associated .png graphic files) attached. However, if I view the message from WebMail, the HTML is rendered. It also displays correctly from an iOS device (Mail App). We have some recipients in the same domain that are hosted on an Exchange server that the domain smarthosts to, and they are able to view the same messages via Outlook as HTML. I will add that Thunderbird clients are also seeing the messages as empty file attachments. I've looked at the raw messages, and outside of not having a <text/plain> part they appear to be formatted correctly. Does anyone have any insight as to what might be causing this, and if there's any workaround within mailenable that would allow us to correct this?
Our Mailenable version is 9.79 and Outlook version is 2016. Transports used in Outlook are POP and IMAP...the issue shows up with either.