How Mailgun and Mailjet by Sinch boost localization ROI with Smartling:


Here’s a closer look at Mailgun and Mailjet by Sinch’s journey to increasing website traffic, saving $180,000, avoiding 2,500 hours of manual work, and more – all through localization.

“So far, in my 25 years or more career in the translation industry, this is the best tool I have found.”

- Alfonso González Bartolessis, Localization Manager at Sinch

About Mailgun and Mailjet by Sinch

Mailgun and Mailjet are both part of Sinch, a communications-platform-as-a-service (CpaaS) that helps businesses deliver unified and personalized experiences through messaging, voice, and email. As part of its email offering, Sinch offers two localized email products: Mailjet and Mailgun by Sinch, both added to Sinch’s portfolio via acquisitions.

Here is how the Mailjet and Mailgun teams overcome localization challenges, serve their global customers at scale, and ensure localization ROI.


When the Mailjet and Mailgun by Sinch teams first started localizing, their process was manual.

After developing a robust content strategy, their next step was to strengthen the localization process in order to further enhance customer relationships in their core markets, such as France, Germany, and Spain, while also expanding into new markets.

Mailjet by Sinch, a company originally founded in France, was producing content for each region without a specific brand guide and standard metrics to assess the quality of their localized content. This resulted in an inconsistent brand voice and inefficient use of their resources.

The need for localization expanded beyond the content department and the company decided to launch the localization of their developer-focused email product: Mailgun by Sinch. The product, marketing, and legal teams began requesting localization. It was time to build a scalable process to manage localization efforts across the company.

The localization team searched for a solution that would allow them to:

  • Internationalize SEO
  • Integrate their content management system (CMS) and other systems with translation management system (TMS)
  • Implement quality standards, reflecting their approved brand voice and terminology in all messaging across all languages
  • Create translation guidelines and workflows
  • Measure return on localization investment
  • Reduce cost and avoid wasting time on project management and task execution

The localization team at Sinch needed a more professional, streamlined, and automated localization solution. They hired Smartling.


Within the first year of their partnership with Smartling, the Mailgun and Mailjet team have improved their time to market, translation quality, and website conversion rate, generating a significant return on their investment in Smartling.

Through Smartling, Mailgun by Sinch localized its entire website.

Faster Time to Market

To boost their time to market,the Mailjet and Mailgun team implemented integrations between Contentful, Zendesk, and Figma and Smartling – all of which reduced team members’ time spent on localization project management and manual tasks.

Automation drives the translation workflows, and now, little to no human interaction is required. It reduces manual tasks such as copying and pasting, sending files via email, uploading and downloading files, and more.

As a result, the team achieved the following:

  • 1.6 million words translated in one year
  • 2,500 hours of manual work saved that has since been reinvested into focusing on building a stronger localization strategy for both existing and new markets

High-Quality Translations

In today’s global markets, quality translation no longer just means error-free. It means the message flows naturally, resonates locally, and the company’s brand and voice show through across all languages. And it’s done with very low edit rates.

To accomplish this, the Mailgun and Mailjet team set a standard using translation guidelines for all target languages, including a brand guide, glossary, and translation memory features. With Smartling’s various translation capabilities, like Machine Translation Post Editing (MTPE), they tailored the translation approach for different types of teams and job requests.

Using the Linguistic Quality Assurance (LQA) feature, the team tracked quality issues such as inconsistency with their glossary, spelling or grammar errors, translation taken out of context, and more so they could be quickly and easily rectified.


After having their Mailjet product localized for three core markets – Germany, Spain, and France –, the Sinch decided to also localize the Mailgun website into German, Spanish, and French.

Within three months, they saw an increase in website visitors from:

  • Germany by 291%
  • Spain by 966%
  • France by 391%

Following the online success, the Mailgun team empowered the sales teams by localizing sales collateral and other assets in German, Spanish, and French, enabling them to sell the Mailgun by Sinch product in their target languages.

Cost Savings

This resulted in a successful year (2022) for Mailgun and Mailjet’s localization strategy. Using Smartling’s automation tools, Sinch saved over $130,000, and an additional $50,000 by using translation memory to store and reuse translated content.

With the streamlined localization process and the saved time and resources, Sinch Email can now tackle more complex and larger projects and expand localization influence to the greater organization.

Thanks to the collaboration with Smartling, both Mailjet by Sinch and Mailgun by Sinch have made significant progress toward its localization objectives and are well-positioned for future growth.