What does Briefkasten look like on HTC?

On HTC it is the design shipped in Sense 8, shown above at full size. Older revisions are listed beneath it.

When did HTC add Briefkasten?

HTC first drew Briefkasten in Sense 7, released 30. März 2015.

HTC Corporation has shipped 2 versions of Briefkasten. Each is dated, so you can see when the design changed.

HTC

HTC Corporation has drawn Briefkasten 2 times. Every revision HTC has shipped is below, newest first.

What does Briefkasten look like on HTC?: On HTC it is the design shipped in Sense 8, shown above at full size. Older revisions are listed beneath it.
When did HTC add Briefkasten?: HTC first drew Briefkasten in Sense 7, released 30. März 2015.
How many times has HTC redrawn Briefkasten?: HTC Corporation has shipped 2 versions of Briefkasten. Each is dated, so you can see when the design changed.

HTC artwork for this emoji spans 2015 to 2016.