How does Mailbox app render responsive HTML emails?

Edit: As of October 2013, Mailbox no longer features full support for media queries. It has been patchy and problematic for the past couple of months, Mailbox are apparently aware of this but there is no known upcoming fix. For the time being, sadly, Mailbox simply does not support responsive emails.

Mailbox.app, the popular mail app for iPhone, only supports one method of responsive HTML email development.

Previously, I used both of these methods interchangeably:

First method: using ‘align’ on tables

Second method: using “display: block” on <td>s

Here are the media queries:

The results in Mailbox show that only the first method actually works.

It’s also worth noting that because of the extra background on Mailbox.app, emails display within a narrower 612px width (on a Retina display; 306 on non-retina).

Comparison of how each client renders responsive email HTML
Comparison of how each client renders responsive email HTML