When you Embed a Video on the cover page of your email, the video may not play in the inbox of your recipients. For security reasons, most email clients like Outlook, Thunderbird and Apple Mail, do not support video playback in the inbox. Unfortunately, this is a security enforced on the mail clients end and cannot be resolved by Poppulo'. If you have correctly embedded your video using our Embed a Video instructions, an image with a play icon will appear in the inbox, indicating that there is video content. The video will play on the email's microsite and when your reader clicks the image in their inbox, they will be taken to the video.
Take a look at https://www.outlook-apps.com/email-video/, for more information.