social/website_mail_snippet_fixed/views/templates.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- © 2016 Antiun Ingeniería S.L. - Jairo Llopis
     License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html). -->

<openerp>
<data>

<!-- Section with 560px width snippets -->
<template id="560px_section_add"
          inherit_id="website_mail.email_designer_snippets">
    <xpath expr="//a[@href='#snippet_email_structure']/.." position="after">
        <li>
            <a href="#snippet_email_560px" data-toggle="tab">
                Fixed 560px Width
            </a>
        </li>
    </xpath>

    <xpath expr="//div[@id='snippet_email_structure']" position="after">
        <div id="snippet_email_560px" class="tab-pane fade">
            <t t-call="website_mail_snippet_fixed.560px_section"/>
        </div>
    </xpath>
</template>

<template id="560px_section"/>

<!-- Base structure for all snippets -->
<template id="snippet">
    <div>
        <div class="oe_snippet_thumbnail">
            <img
                class="oe_snippet_thumbnail_img"
                t-attf-src="/website_mail_snippet_fixed/static/src/img/#{image}.png"/>
            <span
                t-esc="title"
                class="oe_snippet_thumbnail_title"/>
        </div>
        <div
            class="oe_snippet_body"
            style="padding:0px; width:100%; background-color:#ececec; color:rgb(0,0,0); line-height:20px; font-family:Arial,sans-serif; font-size:9pt">
            <table
                style="width: 560px; border-collapse: collapse; background: inherit; color: inherit; background: #FFFFFF"
                cellpadding="0"
                cellspacing="0"
                align="center"
                class="bg_color_picker">
                <t t-raw="0"/>
            </table>
        </div>
    </div>
</template>

</data>
</openerp>