Mariusz O.
100% Job Success
Top Rated Plus

Certified EMAIL EXPERT: Design, HTML: MailChimp, SalesForce, HubSpot

I specialize in creating mobile-responsive emails, and templates that are Dark Mode ready for various platforms such as MailChimp, Salesforce, HubSpot, Campaign Monitor, Constant Contact, SendGrid, iContact, Pardot, Klaviyo, and many others. In September 2015, I was acknowledged by MailChimp for discovering bugs in their new 2015 templates, which helped the company rectify these issues. I am a certified MailChimp Partner Program member, and MailChimp incorporates my HTML/CSS code that correctly renders in Outlook for client emails. OVERVIEW: ★ Member of 30 Upwork Talent Cloud Groups (Microsoft, J&J, Unilever, Netflix, etc.). ★ 14+ years of experience in designing and coding email templates. ★ Over 1800 highly satisfied clients. CERTIFICATES: ★ HubSpot Marketing Software Certification (Provider: Hubspot) ★ Hubspot Contextual Marketing Certification (Provider: Hubspot) ★ Hubspot Email Marketing Certification (Provider: Hubspot) ★ Python Certified (Provider: Alison) ★ Mailchimp Certified (Provider: Mailchimp) ★ "Salesforce for Admins" Certificate (Provider: Linkedin) ★ "Managing DNS Essential Training" Certificate (Provider: Linkedin) ★ "Advanced CSS Media Queries" Certificate (Provider: Linkedin) ★ Google Ads - Measurement Certification (Provider: Google) My biggest CLIENTS: ★ Microsoft, Unilever, Netflix, Toyota, Hyundai, Adobe, BBC, LG, Renault, Fuji, Facebook, Instagram, 3M, Sony, Coca-Cola, Dulux, GLS, Amazon Prime Video, Bayer, Meta. My major SERVICES include: ★ DESIGN & CODE custom email templates, campaigns, automations ★ Programming modules for HubSpot (HubL), Salesforce (AMP Script), Marketo ★ Email deliverability (Setup DKIM / SPF / DMARC) ★ Litmus tests ★ Landing Pages, Signup Forms, and Integrations ★ Designs for Printing (Wedding Albums, Brochures, Flyers, Catalogs, etc.) ★ Gifs ★ Responsive Newsletter Designs and Templates (DARK MODE ready) for Mailchimp, Salesforce, HubSpot, Marketo, Pardot, Klaviyo, Campaign Monitor, iContact, Constant Contact, GetResponse, and more. My English is fluent. I lived and worked for three years in Ireland (Roscommon). SKILLS: Expert Level: HTML5, CSS, Photoshop, Figma, Illustrator, inDesign, AMPscript Average level of knowledge: Python, JavaScript I’m available : Monday - Thursday : 3am EST – 11am EST and 3pm EST – 7pm EST Friday : 3am EST – 11am EST I only work through Upwork. If you want me to work on your project, please create a project on Upwork and invite me to it. I suggest setting up a project that doesn't require a lot of Connects, as I typically reject invitations for such projects.
Work history

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  • HubSpot
  • Pardot
  • Salesforce
  • Email & Newsletter
  • HTML Newsletter
  • Email Template
  • Email Template Development

Get started working with Mariusz quickly with these predefined projects.

Get started working with Mariusz quickly with these predefined projects.

You will get a Pardot drag-and-drop email template.

From $80
2 days delivery

You will get Dark Mode installed in your HTML email template

From $50
2 days delivery

You will get a high-quality mockup of your product

From $57
2 days delivery

You will get a drag-and-drop EMAIL TEMPLATE for your mailing website, for e.g., iContact

From $135
3 days delivery


Endorsements from past clients

"Mariusz does a great job: efficient and professional - if you need assistance with email templates and coding. He's your man. Highly recommended. "

Blair L. | Founder and CEO
Dec 2023


"We have been working with Mariusz on a monthly basis for all our newsletter requirements. Mariusz is definitely a technical expert. He is working fast, and always perfectly. We never faced a single issue since the beginning. But more than anything, he brings value to our team by making the right recommendations and choices. In reality, our main issue is to not have enough work to keep him 100% . Thanks for everything Mariusz!"

Aurelie B.
Jun 2021


"Our company has been an ongoing client of Mariusz O. for 2-3 years now. He designs our monthly newsletter that we send out to our clients, and he's superb to work with! He comes up with designs quickly and is prompt to make adjustments when we have a last-minute addition or idea for our campaigns. Our open and click rates on our emails have seen a steady increase since we started working with Mariusz. And recently we had a client tell us how impressive our email newsletters look every month - a true testament to Mariusz's technical skills and creative abilities. We highly recommend Mariusz and look forward to a long continued partnership with him in the future."

Jeremy S. | Creative Director
Jun 2021


"Mariusz has provided reliable technical support for our program needs, and is a very capable front-end developer. He works efficiently within time constraints, and always produces high-quality, carefully coded content. I highly recommend him."

Jason A.
Jun 2021