HTML Code Requirements and Allowed Tags – ContactMonkey Help Center

The HTML content block supports specific HTML tags and attributes for security and email client compatibility. Use this reference when building custom code.

Structure Requirements

Parent Div Rule

Each HTML block must contain one parent <div> tag. If your code has multiple divs at the same level, wrap them:

✅ Correct:

<div>
  <div>Content 1</div>
  <div>Content 2</div>
  <div>Content 3</div>
</div>

❌ Incorrect:

<div>Content 1</div>
<div>Content 2</div>
<div>Content 3</div>

Allowed HTML Tags

The following tags are supported in HTML blocks:

a, abbr, acronym, address, area, b, bdo, big, blockquote, button, 
caption, center, cite, code, colgroup, dd, del, dfn, dir, div, dl, 
dt, em, fieldset, font, form, h1, h2, h3, h4, h5, h6, i, ins, kbd, 
label, legend, li, map, menu, ol, optgroup, option, p, pre, q, s, 
samp, select, small, span, strike, strong, sub, sup, table, tbody, 
td, textarea, tfoot, th, thead, tr, tt, u, ul, var

Allowed Attributes by Tag

General Attributes

These attributes work on most tags:

style, id, class, data-*, title

Tag-Specific Attributes

Links (<a>):

href, name, target

Images (<img>):

align, alt, border, height, hspace, src, vspace, width, usemap

Tables (<table>):

align, bgcolor, border, cellpadding, cellspacing, width

Table Body (<tbody>):

align, valign

Table Cells (<td>):

align, bgcolor, colspan, height, rowspan, valign, width

Table Rows (<tr>):

align, bgcolor, valign

Table Footer (<tfoot>):

align, valign

Table Headers (<th>):

align, bgcolor, colspan, height, rowspan, valign, width

Table Head (<thead>):

align, valign

List Items (<li>):

type

Image Maps (<map>):

name

Map Areas (<area>):

alt, coords, href, shape, target

Why These Restrictions?

HTML in emails must pass through security filters and work across dozens of email clients. These limitations ensure:

Security: Prevents malicious code from reaching recipients
Compatibility: Focuses on widely-supported HTML elements
Deliverability: Helps emails avoid spam filters

Troubleshooting

My HTML isn't rendering:

Check that all tags are from the allowed list
Verify you have only one parent <div> tag
Ensure all attributes are supported for that specific tag

My styles aren't applying:

Use inline styles with the style attribute
Avoid external stylesheets or <style> tags
Test across multiple email clients