Using CSS media queries to target Apple iPad in both portrait and landscape view.
HTML Email Knowledge Base
Prevent gaps between images in Outlook 2007 – 2013
The Outlook email clients add a spacing above and below images which have a height smaller than 19 pixels.
Remove gaps between images in Gmail and Yahoo! Mail
Gmail and Yahoo! Mail add a spacing between images. This issue first showed up when viewing emails in Firefox and later spread across other modern browsers including IE, Chrome, Opera, and Safari.
Prevent borders on linked images
Some email clients and webmail services such as AOL Mail, Gmail, Lotus, Outlook, Thunderbird, and Windows Mail will display a blue or black border around images that are linked but don’t have a border specified.
.ExternalClass CSS fix for Outlook.com
By default, Outlook.com centers your email by placing it inside a div with a class named “ExternalClass” using the styles display:inline-block; line-height: 131%. These have no effect when using IE, however in every other browser, the email will not be centered.
