The biggest offender is is Outlook on macOS. You can pinch to zoom when editing an email, and it will remember your zoom level for subsequent emails created. T

The biggest offender is is Outlook on macOS. You can pinch to zoom when editing an email, and it will remember your zoom level for subsequent emails created. There's no way to reset it to the default, and so no way to tell even roughly how big the text will look for the recipient (screen size notwithstanding).