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Cloud Fax Services for Popular Webmail Offerings: Email Providers’ Customers can Fax with Retarus

Premium customers of Germany’s two largest email providers can also send and receive faxes. Integrated as a white label solution, Retarus’ proven Cloud Fax Services run in the background.

Initial situation

Popular Email Accounts

More than half of Germany’s internet users have an email account with the two largest German email providers, GMX and WEB.DE. The users’ personal data – from emails, photos, and videos to private documents in the cloud – are protected by numerous security and backup systems.

Both providers were initially established as independent companies and brands in the mid‑1990s with the expansion of the World Wide Web. Today they belong to Germany’s largest internet service provider, United Internet AG. The service provider also has a presence in numerous European countries and the USA, where it markets web hosting, domains, and public cloud infrastructure, among other products and services.

Since their inception, both internet portals have continuously expanded their communication services. These include free email services with unified messaging functions that were integrated early on. Both providers also offer value-added services for paying users such as a fax function, which was operated for a long time using an infrastructure developed in‑house.


Seamless Integration into Webmail Interfaces

For these two email providers, fax is not part of their core business, so they decided to outsource it to a service provider with expertise in this area. Retarus was chosen thanks to simple integration, decades of experience, and provisioning from local data centers. Retarus’ Cloud Fax Services – integrated at the two email providers between December 2021 (outbound) and April 2022 (inbound) – enables both internet portals to offer their users an option for seamless integration in their webmail interface so they can send and receive faxes as they would emails. An incoming fax is converted into a PDF file upon receipt and delivered to the user’s inbox.

The plan rate determines how many fax pages per month are included. Furthermore, the price for sending a page varies, depending on the destination. In addition to the browser interface, customers can also use integrated desktop applications with advanced capabilities.

“Retarus’ Cloud Fax Services are high-performance services that run in the background. They integrate seamlessly into our existing infrastructure so we don’t have to worry.”

Steffen Hubauer, Senior Product Manager, WEB.DE | GMX

Special Challenges / Approach

Customer SIP Trunking Over Leased Lines

Retarus presented its concept to the operators of the two internet portals in March 2020. Once the technical details were clarified, their development teams prepared for the launch in 2021.

As leading German communication and information platforms, both companies want to be a one-stop shop, offering their customers an entire range of communication solutions integrated in one place. In addition to electronic services and sending and receiving letters, these also include fax solutions. To do this, they provide their customers with fax numbers from their own seven-digit number range. The British carrier Plusnet supplies them via customer SIP trunking over leased lines to the Retarus data centers in Munich and Frankfurt.

Within the project, the two email portals have also become the first customers to use Retarus’ new fax configuration API. They use it to activate or deactivate their customers’ incoming fax numbers completely independently; Retarus neither has nor knows any user data. This kind of setup can also be used by other telecommunications service providers who wish to offer customers a fax service.

Retarus Product in Use


A High-Performance Fax Service with High Availability

By outsourcing their fax operations to Retarus, the two email portals can concentrate on their core business consisting of email, cloud, and news, while offering their customers a high-performance fax service with high availability.

All with no additional hardware or software installation and no license fees. Thanks to the pay-per-use concept, Retarus only charges for the fax pages actually sent and received. The myEAS admin portal gives administrators at both providers a complete overview of and control over their Retarus services at all times.

Key Facts

  • Cloud Fax replaces in-house development
  • Seamless integration in the backend and webmailer
  • White label integration with configuration API
  • Contractually binding service level agreements (SLAs)

750,000 Fax Numbers

At the time they switched to Retarus Cloud Fax, the two Internet portals had around 650,000 fax numbers that were active and set up. In addition, there is now another block of 100,000 numbers from which new customers can choose. At go-live in April 2022, the email providers were the Retarus customer with the largest inbound traffic via customer SIP trunking.

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Do you have questions about Retarus, our products and services, or wish to receive further information? Your personal sales representative will assist you with any inquiries. Please contact us!