How to edit an HTML email template without breaking it

This guide assumes you've got a template with edit markers built in — little plain-English comments that tell you exactly what to change. All three of my free LiamMail templates work this way, and so does every custom suite I build. If your template doesn't have markers, the same principles apply; you'll just have to hunt a little harder for your text.

Step 1 — Open it in the right thing

An .html file is just text. Open it in a plain text editor: Notepad on Windows, TextEdit on Mac (switch it to plain-text mode first), or a free editor like VS Code if you want it colour-coded and easier to read.

Step 2 — Look for the markers

Scroll through and you'll see comments like these. Anything inside <!-- ... --> is a note to you — it never shows up in the actual email. The markers point at the exact bit to change:

<!-- ✏️ EDIT: Your headline goes here -->
<h1>Welcome aboard, friend.</h1>

<!-- ✏️ EDIT: Your body text — keep it short & warm -->
<p>Thanks for joining us. Here's what to expect…</p>

You change only the words between the tags — the bit shown in yellow above. The <h1> and <p> around them stay put; they're what makes the heading look like a heading.

Step 3 — Swap your text, images and links

There are really only three kinds of edit you'll ever make:

Anything marked ⛔ DON'T CHANGE is layout — the tables and spacing that keep the email from falling apart in Outlook. Leave those exactly as they are and you can't go wrong.

Step 4 — Add, duplicate or remove whole sections

The best templates are built in blocks — self-contained chunks like a story, a product or a button that you can repeat or remove. The newsletter template, for example, has "story blocks" you can stack as many times as you need. Each one is wrapped in a matching pair of comment markers, so you can see exactly where it starts and ends:

<!-- ════ STORY BLOCK (copy this whole block to add another) ════ -->
<tr>
  ... the heading, image and text for one story ...
</tr>
<!-- ════ /STORY BLOCK ════ -->

To add another section, select everything from the opening <!-- STORY BLOCK --> marker down to the closing <!-- /STORY BLOCK --> marker — both comment lines included — copy it, and paste it directly underneath. You now have two identical blocks; edit the words and images in the new one exactly as before.

To remove a section, delete everything between (and including) those same two markers. The block disappears cleanly and the rest of the email closes up around it.

Not everything is modular — a simple welcome email is usually one fixed layout — but wherever you see paired block markers, that's your licence to add and remove as much as you like.

Step 5 — Get the unsubscribe link right (this one's the law)

Of all the links in the email, one is non-negotiable: the unsubscribe link. In the UK, every marketing email is legally required to give people an easy way to opt out (under PECR and UK GDPR) — and beyond the law, a missing or broken unsubscribe is one of the fastest ways to get marked as spam, which wrecks your delivery to everyone else.

In a good template you'll see a placeholder like href="{{unsubscribe}}" in the footer. That {{unsubscribe}} isn't a real link yet — it's a merge tag your email platform swaps for a proper, personalised unsubscribe link when it sends. The catch is that every platform uses a different tag:

Two rules: never delete the unsubscribe line, and always send yourself a test and actually click it before the email goes to your list. While you're down there, make sure your real business name and a genuine postal address are in the footer too — that's also a legal requirement for marketing email.

Step 6 — Make a plain-text version

Every email actually has two versions: the designed HTML one, and a plain-text fallback. Some inboxes, smartwatches and privacy-focused apps show the plain-text one — and a missing or messy plain-text version can quietly hurt your deliverability.

Rather than let your platform auto-generate a rough one, paste your copy into my free Plain Text Email Generator. It gives you a clean, properly spaced text version you can drop straight in. It's one of ten free tools in the email campaign toolbox.

Step 7 — Paste it into your email platform

Now you send it. Every major platform has a "paste in your own HTML" route — you don't rebuild the email in their editor, you just drop in the file you've edited:

Copy everything from the file — from the very first line to the very last — not just the visible text. Then send yourself a test and open it on your phone as well as your computer before it goes anywhere near your list. If something looks off, undo your last change and test again; you've almost certainly nudged a tag you didn't mean to.

Before you hit send: are you allowed to email them?

A perfect template sent to the wrong list is still a problem. Before anything goes out, be clear on why you're allowed to email each person. In the UK this comes down to two buckets:

If you're honestly not sure your list is clean — addresses collected without clear consent, no record of who opted in, a pile of contacts you've "always had" — it's worth sorting before you press send, not after a complaint. That's exactly what my email list health & GDPR check is for: reviewing how addresses were collected, fixing consent and unsubscribe handling, and cleaning the list so what you send is both legal and more likely to land. There's a fuller primer in the GDPR & email lists guide too.

I'm a designer, not a lawyer or your compliance officer — this is general guidance, not legal advice. For the detail, the UK ICO's direct-marketing guidance is the authority.

That's it

Open in a plain editor, change the marked bits, copy or delete whole blocks to resize the email, set your unsubscribe tag, generate the plain-text version, paste into your platform, send a test. Do it once and the next one takes five minutes. Grab the three free templates here and try it on a real one.

When you'd rather not

Editing a template is genuinely easy once it's built well — but building one that's bulletproof across Outlook, Gmail and Apple Mail, in your brand, with your fonts and colours baked in, is the fiddly part. That's the bit I do for you. If you'd like a proper set of editable templates designed around your brand instead of mine, that's the custom email template service. You still get the easy-edit markers — they're just wrapped around your own look.