HTML Email Development Services
Pixel-Perfect Emails That Render Everywhere

We build responsive HTML email templates that render flawlessly across Gmail, Outlook, Apple Mail, and 90+ email clients. From campaign templates to full transactional email suites — hand-coded, tested, and ready to deploy.

Skills & Platforms

We code for every major ESP and test across every major email client — no exceptions.

HTML Email Coding (Tables & MSO)Responsive Email DesignGmail & Outlook CompatibilityDark Mode Email SupportLitmus & Email on Acid TestingTransactional Email TemplatesEmail Campaign TemplatesNewsletter TemplatesKlaviyo Template DevelopmentMailchimp Template CodingHubSpot Email TemplatesSalesforce Marketing CloudAMP for EmailEmail Accessibility (WCAG)Plain-Text Fallback Versions

Engagement Options

From a single template to a full retainer — we fit around your send schedule.

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One-Off Template

A single HTML email template designed, coded, and tested across 90+ clients. Perfect for a hero campaign or a transactional trigger.

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Template Suite

A set of 5–20 branded email templates: welcome series, cart abandonment, receipts, newsletters, and more — built to a consistent design system.

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Ongoing Retainer

Monthly HTML email development support for teams who send regularly — new templates, template edits, A/B variants, and dark-mode updates.

Why Choose 1Solutions for HTML Email Development?

We build emails that survive the inbox — Outlook, dark mode, mobile, and everything in between.

Outlook-Proof Coding

Outlook uses Microsoft Word's rendering engine, which breaks modern CSS. We use MSO conditional comments, VML, and table-based layouts that look perfect in Outlook 2007–2023.

Dark Mode Ready

40%+ of users read email in dark mode. We code media query overrides that preserve your brand in dark environments — not just let Outlook invert your colours.

90+ Client Testing

Every template is tested in Litmus or Email on Acid across Gmail, Outlook, Apple Mail, Samsung Mail, and Thunderbird before delivery.

Responsive on Every Device

Fluid-hybrid layouts that adapt from 600px desktop to 320px mobile without breaking your header, hero, or CTA.

ESP-Ready Delivery

Templates delivered in your ESP's format — Klaviyo drag-and-drop blocks, Mailchimp editable regions, HubSpot custom modules, or raw HTML.

Accessibility First

Semantic HTML, role="presentation" on layout tables, ALT text on all images, and sufficient colour contrast — so your emails work for screen reader users too.

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Email Templates Built
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ESP Platforms Supported
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Client Satisfaction
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Email Clients Tested

Our Email Development Process

Brief to inbox-tested delivery in 4 steps — no shortcuts, no builders, no broken rendering.

01

Brief & Design

We review your brand guidelines, ESP, and email objectives — then produce a design mockup for approval before any coding begins.

02

Code & Build

We hand-code the template using table-based HTML, MSO conditionals, and fluid-hybrid responsive techniques — no drag-and-drop shortcuts.

03

Cross-Client Testing

We test the coded template across 90+ email clients in Litmus, verify dark mode behaviour, and check plain-text rendering.

04

Deliver & Deploy

We deliver the template in your ESP's format — with editable regions, content blocks, and a handoff guide — ready to send.

Frequently Asked Questions

Common questions about our HTML email development services.

Why hand-code HTML emails instead of using a builder?+
Which email clients do you test in?+
Can you build templates inside Klaviyo, Mailchimp, or HubSpot?+
Do you support AMP for Email?+
How long does it take to build an HTML email template?+
Do you sign NDAs?+

Ready to Build HTML Emails That Actually Render?

Tell us your ESP, send volume, and template needs — we'll quote within 24 hours and deliver your first template in under a week.

Get a Free Template Quote →