HTML5 video, iOS 11 (11.4.1) and iPhone X
(Reposting this as my original message inexplicably disappeared).
I am looking to use HTML5 video in an email campaign and from testing have discovered that the video does not playback in the native Mail application on the latest iOS 11.4.1 on a iPhone X, whereas it will playback in the Mail application on the exact same iOS 11.4.1 version on earlier iPhone devices that I have tested, such as an iPhone 6 and iPad Air.
I have tested this on two separate iPhone X devices, both returning the same result; poster image with no playback controls presented.
Has anyone encountered this and know why iPhone X running iOS 11.4.1 will not playback HTML5 video in the Mail application, compared to earlier iPhone models with same iOS that do?
My markup is below (example below showing absolute URLs replaced with relative for example).
<video controls playsinline preload="metadata" poster="example-video-poster.jpg" width="480" height="270">
<source src="example-video.mp4" type="video/mp4">
<source src="example-video.webm" type="video/webm">
<source src="example-video.ogv" type="video/ogg">
<a href="" target="_blank"><img src="example-video-fallback.jpg" alt="Video" title="Watch video in web browser" width="480"></a>
While the wisdom online is that HTML5 video is supported in the Mail application on iOS11, its implementation seems to be unstable/unreliable. I have read comments online such as closing all running applications, which presumably frees up system resources, then reopening the Mail application which can encourage playback of the video in the email. This certainly was the case for an iPhone SE that I tested, but is clearly not a practical solution for a live campaign.
I'm close to deciding that in practice, the HTML5 video support implementation in the Mail app is not reliable enough for email.