You will get Dark Mode installed in your HTML email template
Top Rated
Top Rated
Project details
I will add Dark Mode and test it on the most popular email clients using Litmus. I will send you the link to these tests.
My Upwork stats:
★ Over 1,800 highly satisfied clients
★ Total jobs: 4,000
★ Total earned: Over $600,000
★ Total hours worked: 14,000
★ Member of 31 Talent Clouds
My Upwork stats:
★ Over 1,800 highly satisfied clients
★ Total jobs: 4,000
★ Total earned: Over $600,000
★ Total hours worked: 14,000
★ Member of 31 Talent Clouds
Email Platform
GetResponse, ActiveCampaignWhat's included
| Service Tiers |
Starter
$50
|
Standard
$60
|
Advanced
$70
|
|---|---|---|---|
| Delivery Time | 2 days | 2 days | 2 days |
Responsive Design | - | - | - |
Custom Graphics | - | - | - |
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SS
Stefania S.
Jun 30, 2026
TV Subscriptions User Feedback (Poland)
It was really lovely working together, and we really appreciate your prompt responses and diligent work. I hope we can collaborate on similar studies in the future!
The work done will help our client improve their product for users across various European markets.
The work done will help our client improve their product for users across various European markets.
jx
joseph x.
Jun 23, 2026
html email signature
jx
joseph x.
Jun 23, 2026
email signature
MZ
Mike Z.
Jun 9, 2026
Bulk and drip email marketing
NS
Nichole S.
Jun 5, 2026
Professional Outlook Signature Design
NA
About Mariusz
EXPERT EMAIL DEVELOPER || Email Marketing Strategist & AI Architect II
99%
Job Success
Opole, Poland - 5:03 pm local time
With 15+ years of experience, 4,000+ projects delivered for 1,900+ clients worldwide, I build production-ready email systems - not just templates - combining clean HTML/CSS, lifecycle automation, marketing strategy, deliverability expertise, and AI-driven workflows under one roof. Top Rated Plus on Upwork with $700K+ in earnings.
What I do:
1. Email Development (Core)
Custom HTML/CSS email builds - mobile-responsive, dark-mode-ready, cross-client tested. I work across Mailchimp, HubSpot, Salesforce / Pardot, Marketo, Klaviyo, ActiveCampaign, Campaign Monitor, SendGrid, and Iterable. In 2015, Mailchimp recognised me for identifying and fixing critical rendering bugs in their templates. Certified Mailchimp Partner.
2. Email Marketing Strategy & Execution
End-to-end email marketing - audits, campaign planning, segmentation, lifecycle automation (welcome, nurture, re-engagement, winback), A/B testing, and performance optimisation. I build scalable, compliant email programs with predictable long-term performance. I handle both strategy and execution end-to-end.
3. AI Architecture & Intelligent Automation
I build AI-powered audit and automation systems connected directly to your ESP/CRM via MCP servers. AI analyses your flows, campaigns, deliverability, and engagement data in real time - producing structured audit reports and prioritised fix lists. Examples: automated Klaviyo flow audits with copy rewrites, real-time deliverability monitoring, and engagement scoring. I also build RAG MCP servers that let AI reference your internal docs, brand guidelines, and performance history during audits and content generation.
4. Front-End & Automation Development
Custom applications, internal tools, dashboards, and integrations using JavaScript, Python, React, Google Apps Script, and n8n. I connect CRMs, ESPs, databases, Google Sheets, and APIs into unified automated workflows.
Core services:
★ Custom email development (HTML/CSS, dark mode, responsive, cross-client)
★ Email marketing strategy, audits & campaign execution
★ AI-powered ESP/CRM audits via MCP server integration
★ RAG MCP servers for context-aware AI recommendations & content generation
★ Lifecycle automation (welcome, onboarding, nurture, re-engagement, winback, lead scoring)
★ Deliverability setup & troubleshooting (SPF, DKIM, DMARC, sender reputation)
★ Segmentation strategy (openers, clickers, inactive users, RFM, predictive)
★ A/B testing, reporting & performance optimisation
★ Advanced ESP customisation (HubSpot HubL, Salesforce AMPscript, Marketo Velocity)
★ AI agents & n8n automation systems
★ CRM & ESP integrations (HubSpot, Salesforce, Marketo, Mailchimp, Klaviyo, ActiveCampaign)
★ Custom Google Sheets & Apps Script solutions (dashboards, triggers, integrations)
★ API-based integrations & webhook workflows
★ Cross-client email testing (Litmus, Email on Acid, dark mode, Outlook VML fixes)
Why work with me:
★ 15+ years in email development and email marketing
★ 4,000+ projects for 1,800+ clients (Microsoft, Netflix, Unilever, Toyota, Adobe, BBC, Meta, Amazon Prime Video, TikTok, Adidas, Sony, Coca-Cola, Hyundai, LG, Renault, Bayer, 3M, and more)
★ Member of 32 Upwork Talent Cloud groups (Enterprise Professionals, Microsoft UTC, Netflix Print Production, Unilever, Tata Communications, Holland & Barrett, Janus Henderson, and others)
★ AI-powered audit and automation capabilities (MCP + RAG architecture)
★ End-to-end ownership - strategy, development, execution, optimisation
★ Clean, maintainable code and scalable architecture
Certificates: HubSpot Marketing Software, HubSpot Email Marketing, HubSpot Contextual Marketing, Mailchimp Email Automations, Mailchimp Foundations, Python (Alison), Salesforce for Admins, Managing DNS, Advanced CSS Media Queries, Google Ads Measurement.
Skills: HTML5, CSS, Email Development, Email Deliverability, AMPscript, HubSpot HubL, Marketo Velocity, JavaScript, Python, React, Google Apps Script, n8n, APIs & Webhooks, MCP Servers, RAG Architecture, AI Agents, Marketing Automation, CRM Integrations
I use AI as a development and analysis accelerator - speeding up coding, testing, auditing, and iteration - while maintaining full control over architecture, logic, and production quality.
Availability:
★ Mon–Thu: 3:00 AM – 11:00 AM EST, 3:00 PM – 7:00 PM EST
★ Friday: 3:00 AM – 11:00 AM EST
Steps for completing your project
After purchasing the project, send requirements so Mariusz can start the project.
Delivery time starts when Mariusz receives requirements from you.
Mariusz works on your project following the steps below.
Revisions may occur after the delivery date.
Dark Mode
I will add Dark Mode to your HTML email and run Litmus tests