A Stensul alternative built on the HTML you already have.
Modular Mail is a CMS for email. Your developer marks the editable parts of your existing HTML with one attribute, data-mm, marketers build each campaign by filling in fields, reviewers approve on the same screen, and the finished HTML is pasted into Marketo, Salesforce Marketing Cloud, Braze or any other ESP.
Send us one of your Stensul emails when you book and we'll rebuild it before the call.
The autumn edit is here
Waxed jackets, wool layers and trail boots for the wet months.
Why teams look for a Stensul alternative
Stensul is built for regulated enterprises, and in those teams it does its job well. Email is still the channel UK marketers report returning almost £41 for every £1 spent (DMA, 2026), so the production tool behind it matters. When a team looks elsewhere, it's usually for one of these reasons.
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.
Modular Mail and Stensul at a glance
| What | Stensul | Modular Mail |
|---|---|---|
| Where templates live | Stensul's modular builder, with governed modules designed during implementation | Your own HTML, with one data-mm attribute on each editable part |
| Who builds the modules | Stensul's team, or developers coding Custom Elements | Your developer, your agency or our onboarding team, in your HTML |
| Building a campaign | Marketers assemble governed components | Marketers add modules, drag them into order and fill in fields |
| Brand control | Lock fonts, colours and layouts | Styles stay in the template's HTML; fields carry limits and approved options |
| Review and sign-off | Approvals embedded in the workflow | Comments on the email or one part of it, review requests and approval on record |
| Getting it to your ESP | Direct integrations with Marketo, Eloqua, Salesforce Marketing Cloud, Iterable, Braze and more, or HTML download | Copy or download the HTML, for any ESP |
| Translation and landing pages | Both built in | Neither |
| Render testing | Native render and accessibility checks | Test sends to real inboxes; your own testing tool for the rest |
| Who it's built for | Enterprise campaigns in regulated industries | Marketing teams and agencies of any size |
| Pricing | Custom quote, in four packages | Published on our pricing page |
Stensul's details are from stensul.com, checked on 3 November 2026. Modular Mail isn't affiliated with Stensul. Updated 3 November 2026.
What moving from Stensul looks like
Template conversion is part of onboarding on every plan. We scope it with you at kickoff, and your developer or agency can do as much of it as they like.
When to stay with Stensul, and when to switch
Modular Mail has no ESP connectors, no translation, no landing pages, and no render testing of its own beyond test sends to real inboxes. If those are why you chose Stensul, it's still the right choice.
Stensul is the better fit if
- You're in a regulated industry and need approval chains with legal and compliance in them
- You push emails into Marketo, Eloqua, SFMC or Iterable through a connector
- You localise the same campaign into several languages
- You want one vendor to design the modules and run the implementation
Modular Mail is the better fit if
- Your templates are HTML a developer or agency built, and you want them to stay in code you own
- One team sends from one or two ESPs and already pastes HTML in
- You want the price before the first call
- You'd rather your own developer or agency set the templates up, with our help
Is Modular Mail cheaper than Stensul?
Stensul quotes each customer, so there's no list price to compare. Ours are public: Starter for one team with 2 editors, Team for 10, and Enterprise for agencies and larger companies. Reviewers are free on every plan. See pricing
Can you convert our Stensul templates?
Yes. Template conversion is part of onboarding. We rebuild each module from an exported email, mark the editable parts with data-mm and scope the work with you at kickoff. Your developer can take on as much of it as they like.
Does Modular Mail connect to Marketo or Salesforce Marketing Cloud directly?
No. You copy or download the HTML and paste it into the ESP, which works with any platform that accepts HTML. There's no API connection to maintain.
How does governance work without locked components?
The lock is the template itself. Layout, fonts, colours and spacing are in the HTML and can't be edited in a campaign. Each editable part is a field, with a character limit, a required flag or a list of approved options where the brand needs one.
Can legal or compliance review an email before it goes out?
Yes. Add them as reviewers. They get an email with a link that opens the campaign in comment mode, leave comments on the module that needs changing, and approve when it's right. The campaign records each approval, and shows when the email has been edited since.
Will our emails look different?
No. The template is your HTML with the editable parts marked, so the design stays as it was coded.
Is Modular Mail also an alternative to Knak?
Yes, for the same kind of team. The Knak page covers the differences in Knak's own terms. Modular Mail as a Knak alternative
What other ways are there to let marketers edit our HTML?
Your ESP's own editable regions, a visual builder that imports the HTML, a developer on every change, or an email CMS. One page compares the four. How to let marketers edit HTML email templates
Can we try it before a demo?
Yes. Every template in the library opens in the editor with no account, so you can fill in fields, reorder modules and export the HTML first. Open a template
See one of your Stensul emails in Modular Mail.
Send us a recent campaign and we'll rebuild it as a Modular Mail template before the call, so you can judge the editor on your own design.