Working with custom HTML

The Custom HTML content block allows you to easily add your own HTML code to an email message that you are designing with the drag and drop builder. It’s as simple to use as a text block.


HTML experts only

Using your own code may affect how the message is rendered in email clients, preventing it from adjusting to the screen size (i.e., the "responsiveness" of the message). Make sure to use HTML that is email compliant and responsive.

Why use custom code?

There are many scenarios in which it makes sense to add your own HTML code:

Adding more customised content

You are not limited by a set of predefined parameters and can therefore have more granular control of the styles applied.

Adding HTML 5 video, anchor links, etc

You can now add content that is not available as a standard content element in the editor (HTML 5 video, anchor links, etc.).

Adding advanced effects with CSS

Animation effects are not widely supported by all email clients, but when managed correctly they can help your message get viral.

Adding live content from external providers

Product recommendations, dynamic ads, personalised maps, all of this advanced content can now be easily included in a message created with the drag and drop builder. Just copy and paste the code provided to you by the vendor that you are working with.

Adding HTML code

To add your code, drag an HTML content element into your message. It can be positioned alone, with other HTML content items, or mixed with other types of content.

The newly inserted content block will show some default placeholder text. Click on it and the right-side property panel will display the HTML code editing pane, where you will find some placeholder code inside the editing area:


Paste your own HTML code or write it directly in the editing area. The system will highlight your syntax and indent your code to make it more readable.

Is dynamic content allowed?

Yes, you can use the HTML block to add dynamic content, see our guide, Personalisation and dynamic programmable content, for more detail on how dynamic content works and how to use it.


In the email builder, dynamic syntax can be added directly without needing to be enabled first.

Valid HTML tags

The HTML content will automatically correct some issues like HTML tags that are left open, and strip out code that cannot be used, such as script tags or iframe tags (these code tags are not allowed by the majority of email clients, causing deliverability problems or security risks). Review the list of allowed HTML tags and attributes below:

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, u, tr, tt, u, ul, var
general attributes: style, id, class, data-*, title
a: href, name, target
img: align, alt, border height, hspace, src, vspace, width, usemap
table: align, bgcolor, border, cellpadding, cellspacing, width
tbody: align, valign
td: align, bgcolor, colspan, height, rowspan, valign, width
tr: align, bgcolor, valign
tfoot: align, valign
th: align, bicolor, colspan, height, rowspan, valign, width
thead: align, valign
li: type
map: name
area: alt, coords, href, shape, target