Avoid these

  • position (Yahoo, Gmail)
  • box-shadow (Yahoo, Gmail)
  • height (Outlook)
  • width in p/div (Outlook)
  • padding in p/div (Outlook)
  • data-URI (all webmail)

Basic layout

<table cellpadding=0 cellspacing=0"
  <tr>
    <td width=auto>
    <td width=600px background=white>
    <td width=auto>

Responsive

@media only screen and (max-device-width: 480px)