You have to modify *all* the e-mail templates you're using to use a table-based layout instead of div's. Here's my checkout template (which has most all of the sections used in others) .. your colors may vary:

Code:
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=$CHARSET" />
<base href="$BASE_HREF" />

<style type="text/css">
body {background-color:#c1d198; color:#000000; font-family:Verdana, Arial, Helvetica, sans-serif; text-align:center;}
a:link {color:#0066cc;}
a:hover {background-color:#eeeecc; color:#0066cc;}
a:visited {color:#0066cc;}
.holder {background-color:#f9f9f9; border:1px solid #696363; font-size:9px; text-align:left; width: 550px;}
.header {font-size:10px; padding:0px; width: 550px;}
.content {font-size:10px; padding:5px; width: 550px;}
.footer {border-top:1px solid #696363; font-size:9px; text-align:center; width: 550px;}
.extra-info {background-color:#cccc99; border:1px dashed #696363; font-size:10px; margin-top:10px; padding:5px; width: 550px;}
.content-line {padding:5px; font-size:10px;}
.content-line-title {font-weight:bold; font-size:11px; padding-top:3px;}
.order-detail-area {background-color:#CCCC99; border:1px #696363; padding:2px; font-size:10px; width: 542px;}
.product-details {font-size:10px;}
.product-details-num {font-size:10px; font-weight:bold;}
.order-totals-text {font-size:10px; font-weight:bold;}
.order-totals-num {font-size:10px; }
.comments {background-color:#BBCA93; border:1px #696363; padding:2px; font-size:10px; width: 542px;}
.address-block {background-color:#c8d79c; border:1px solid #696363; margin-top:3px;}
.address {font-size:10px;}
.payment-detail, .payment-footer {font-size:10px;}
.extra-info {background-color:#cccc99; border:1px solid #696363; font-size:10px; margin-top:10px; padding:5px; width: 550px;}
.extra-info-bold {font-weight:bold;}
.disclaimer {background-color:#f9f9f9; border:1px solid #696363; font-size:10px; margin-top:10px; padding:5px; width: 550px; text-align: center;}
.disclaimer1 {color:#666666; padding:5px;}
.disclaimer1 a:link {color:#666666;}
.disclaimer1 a:visited {color:#666666;}
.disclaimer2 {color:#666666; padding:5px;}
.copyright {border-bottom:0px solid #696363; padding:5px;}

</style>
</head>

<body>
<table width="100%" cellspacing="0" cellpadding="0">
  <tr>
    <td align="center">
      <table class="holder" width="550" border="0" cellspacing="0" cellpadding="0">

        <tr class="header">
          <td align="left" height="108">
            <img src="email/header.jpg" width="200" height="108" />
          </td>
        </tr>

        <tr class="content">
          <td>
            $EMAIL_TEXT_HEADER $INTRO_STORE_NAME<br/><br/>
            $EMAIL_FIRST_NAME $EMAIL_LAST_NAME,<br/>
            $EMAIL_THANKS_FOR_SHOPPING<br/>
            $EMAIL_DETAILS_FOLLOW
          </td>
        </tr>

        <tr class="content-line">
          <td>
            $INTRO_ORDER_NUM_TITLE $INTRO_ORDER_NUMBER&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;$INTRO_DATE_TITLE $INTRO_DATE_ORDERED
          </td>
        </tr>

        <tr class="content-line">
          <td><a href="$INTRO_URL_VALUE">$INTRO_URL_TEXT</a><br/></td>
        </tr>

        <tr>
          <td class="content-line"><strong><br/>$PRODUCTS_TITLE</strong></td>
        </tr>

        <tr class="order-detail-area">
          <td>$PRODUCTS_DETAIL</td>
        </tr>
        <tr class="order-detail-area">
          <td>$ORDER_TOTALS</td>
        </tr>

        <tr class="comments">
          <td>$ORDER_COMMENTS</td>
        </tr>

        <tr class="content_line">
          <td><strong><br/>$HEADING_ADDRESS_INFORMATION<br/></strong></td>
        </tr>

        <tr>
          <td>
            <table class="address-block" border="0" width="550" cellspacing="0" cellpadding="2">
              <tr>
                <td valign="top" width="275">
                  <table border="0" width="275" cellspacing="0" cellpadding="2">
                    <tr>
                      <td class="content-line-title"><strong>$ADDRESS_DELIVERY_TITLE</strong></td>
                    </tr>
                    <tr>
                      <td class="address">$ADDRESS_DELIVERY_DETAIL</td>
                    </tr>
                    <tr>
                      <td class="content-line-title"><strong>$SHIPPING_METHOD_TITLE</strong></td>
                    </tr>
                    <tr>
                      <td class="content-line">$SHIPPING_METHOD_DETAIL</td>
                    </tr>
                  </table>
                </td>
                <td valign="top" width="275">
                  <table border="0" width="275" cellspacing="0" cellpadding="2">
                    <tr>
                      <td class="content-line-title">$ADDRESS_BILLING_TITLE</td>
                    </tr>
                    <tr>
                      <td class="address">$ADDRESS_BILLING_DETAIL</td>
                    </tr>
                    <tr>
                      <td class="content-line-title"><strong>$PAYMENT_METHOD_TITLE</strong></td>
                    </tr>
                    <tr>
                      <td class="payment-detail">$PAYMENT_METHOD_DETAIL</td>
                    </tr>
                    <tr>
                      <td class="payment-footer">$PAYMENT_METHOD_FOOTER</td>
                    </tr>
                  </table>
                </td>
              </tr>
            </table>
          </td>
        </tr>

        <tr class="footer">
          <td class="copyright">$EMAIL_FOOTER_COPYRIGHT</td>
        </tr>

        <tr>
          <td>
            <table class="disclaimer" width="550" border="0" cellspacing="0" cellpadding="0">
              <tr class="disclaimer1">
                <td>$EMAIL_DISCLAIMER</td>
              </tr>
              <tr class="disclaimer2">
                <td>$EMAIL_SPAM_DISCLAIMER</td>
              </tr>
            </table>
          </td>
        </tr>

        <tr>
          <td>
            $EXTRA_INFO
          </td>
        </tr>
      </table>
    </td>
  </tr>
</table>
</body>
</html>