But on some user's Outlook for Windows email client, the email will show HTML code, as follow:
For example on my Outlook for web and my Outlook for Windows it is working well as follows, without any HTML code:
Any advice?

But on some user's Outlook for Windows email client, the email will show HTML code, as follow:
For example on my Outlook for web and my Outlook for Windows it is working well as follows, without any HTML code:
Any advice?