How do you let marketers edit custom HTML emails in Iterable?
Iterable's Side by Side editor takes a pasted HTML template and shows it beside a preview, and its Drag and Drop editor lets anyone build from blocks. Neither turns a custom-coded template into fields a marketer can fill, so a custom design is edited in code or rebuilt in blocks. Modular Mail, a CMS for email, adds the missing step: your developer marks the editable parts of the HTML with one attribute, data-mm, your team fills in fields, and the finished HTML is pasted into Iterable's Side by Side editor, or into Braze, Salesforce Marketing Cloud or Marketo if you send from those too.
Updated 3 November 2026. Book a demo and we'll rebuild one of your Iterable emails before the call.
The autumn edit is here
Waxed jackets, wool layers and trail boots for the wet months.
The custom template trade-off in Iterable
Iterable's three editors each suit a different team, and a custom HTML template fits only one of them. Litmus found in 2026 that 78% of teams produce and deploy an email in three days or less; the ones editing Handlebars by hand tend to be the exception.
Sources: Iterable documentation, Template editors overview, Drag and Drop editor, Introduction to Snippets, Personalizing templates with Handlebars.
We used to wait three to five days for dev to update our email templates. Now my team builds campaigns in an afternoon. Same custom designs, zero technical dependency.
How it works with Iterable
Custom templates in Iterable, before and with Modular Mail
| Task | Side by Side with custom HTML | Modular Mail with Iterable |
|---|---|---|
| Editing content | The code, beside a preview | Anyone on the team, in content fields |
| Editing layout | Open to anyone who can edit the HTML | Locked in the template |
| Adding a new section | A developer writes more HTML, or the template is rebuilt in Drag and Drop | Pick a module from your library |
| Shared parts | Snippets, inserted at send time | Modules, published once to the library; Snippets still work after the paste |
| Review and approval | Your team's own process | Comments on one module, review requests and approval on record |
| Sending, journeys and Handlebars | Iterable | Iterable, unchanged |
Iterable's details are from its support centre, checked on 3 November 2026.
Questions Iterable teams ask
Does Handlebars survive export?
Yes. Handlebars typed into a field, such as {{firstName}}, exports as written and Iterable renders it at send time. Keep {{unsubscribeUrl}} and any conditional logic in the footer or the unmarked parts of a module, where no field can overwrite them.
Can we still use Snippets and data feeds?
Yes. Paste the exported HTML into Side by Side and add Snippet references and data feed fields there, as you do now. Iterable inserts them when it sends.
Does it work for journeys as well as campaigns?
Yes. The pasted HTML becomes an Iterable template, and a template can be used by a campaign or a journey touchpoint like any other.
Do we have to rebuild our templates in Drag and Drop?
No. Keep them as HTML. Iterable's docs say a Side by Side template can't be converted into Drag and Drop anyway, and with Modular Mail there's no need: the editing happens before the paste.
Is there a direct Iterable integration?
Not an API connection, and Modular Mail keeps no version history. You copy or download the HTML and paste it into Side by Side, so there's nothing to maintain when Iterable updates an editor.
Can we try it without an account?
Yes. Every template in the library opens in the editor with no sign-up. Fill in a few fields, export, and paste the HTML into a Side by Side template to see it in Iterable. Browse the templates
Do we have to leave Iterable?
No. Iterable keeps the sending, the journeys, the segmentation and the reporting. Modular Mail only changes where the email is built.
See your own email in Modular Mail.
Send us a recent campaign. We'll rebuild it before the call, so you can see exactly how your team would work.