I replied in the other topic you created.
The mobile view having been removed affects stock Android Email (and btw, it zooms almost "to infinity") and K9 mail. Obviously I can't speak for all other mail apps.
From developer documentation:
http://developer.android.com/guide/webapps/migrating.html#ColumnsThe NARROW_COLUMNS value for WebSettings.LayoutAlgorithm is not be supported in the new WebView.
Caution: These APIs are not supported on Android 4.4 and higher at all. Even if your targetSdkVersion is set to "18" or lower, these APIs have no effect
Additionally, the SINGLE_COLUMN value—which was previously deprecated—is also not supported in the new WebView.