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Swisscom migrates millions of Bluewin email accounts to the cloud with zero downtime
We helped Swisscom migrate petabytes of email data to the AWS cloud, ensuring a seamless transition for millions of customers and accounts. Our collaboration helped modernise an aging infrastructure, enabling long-term scalability and stability while accelerating time-to-market.
Project overview:
Several petabytes of data and millions of email accounts are successfully migrated to the cloud with zero downtime.
Secure, scalable AWS cloud infrastructure boosts efficiency and sets a new standard for future cloud projects.
Together, Zühlke and Swisscom navigate unchartered cloud territory with confidence.
Seizing the cloud opportunity
Swisscom is the leading telecommunications company in Switzerland, offering mobile, Internet and TV, as well as comprehensive IT and digital services to private and business customers. Bluewin Mail is Swisscom’s well-known email service.
Bluewin Mail’s service was running on aging software and hardware, so a system upgrade was inevitable. The Bluewin Mail team faced a pivotal decision – invest in modernising the on-premises solution or migrate to the public cloud. Swisscom has trusted our expertise for over two decades to modernise the company’s application landscape, master data management, and more. So, Bluewin Mail’s management team turned to us for help from the start, to ensure a seamless and secure transition to the cloud.
Bridging legacy and cloud: a two-stream approach
To complete Bluewin Mail’s transition to the cloud, two projects had to run in parallel:
- Mail platform’s cloud migration: the customer-facing service needed to be renewed and deployed on a new cloud-based infrastructure.
- Integration layer development: the cloud-based mail platform had to integrate with all relevant Swisscom systems, enabling seamless self-service provisioning, mail ordering, billing, and settings management for the company’s users.
Both projects had to be executed in parallel, ensuring seamless integration between the new mail platform and its integration layer.
“Zühlke supported Swisscom on all aspects of the project and provided high-quality consulting and software engineering we are still happy with months after the project's end.”
Migrating a mail platform to the cloud
Swisscom’s Bluewin Mail team was one of the first in the company looking to move large workloads to the cloud. So, we started by working closely with Swisscom’s team to assess the feasibility of cloud adoption versus maintaining an on-premises infrastructure. We engaged with internal stakeholders, mapped out the existing infrastructure, and compared cost, performance, and scalability implications.
Key considerations included:
- The need for scalable compute power to support millions of customers and email accounts
- The availability of storage for several petabytes of data
- The speed at which the target infrastructure could be built
- The speed at which cloud expertise could be built within the organisation
Due to a significant long-term partnership between AWS and Swisscom, AWS was chosen as the cloud platform from the outset.
Drawing on our extensive experience in running successful cloud projects and deep expertise in the AWS platform, we worked closely with Swisscom to design a secure, reliable, and cost-effective cloud architecture. By leveraging AWS’s frameworks and best practices, including the AWS Well-Architected Framework, we ensured the solution adhered to AWS's recommended standards.
At the time of our migration, Swisscom was in the process of developing internal cloud migration standards. As early adopters, we had to move forward without the benefit of finalised guidance or guardrails. So, our cloud transformation experts played a key role in defining best practices and ensuring a seamless transition.
The project team managed to maintain the speed of the migration whilst adapting to changes. Throughout the process, we provided valuable feedback to Swisscom's cloud team, helping them optimise their standards. This collaboration ensured that large, complex projects, like the Bluewin Mail solution, would benefit from relevant guardrails.
Throughout the project, knowledge-sharing was key. We conducted collaborative pairing sessions, mentoring, and hands-on workshops to upskill internal developers and ensure long-term maintainability.
Developing a robust integration layer
Beyond migrating the mail platform, we needed to ensure that it seamlessly connected with the broader Swisscom ecosystem, while orchestrating the different components of the mail solution.
Together with Swisscom, our software engineers built a Java-based microservices integration layer that connected the components of the new Bluewin Mail platform to Swisscom’s other business areas, including:
- Billing management
- Permission management
- Notification management
- Subscription management
Overcoming key challenges
The ambitious AWS cloud migration came with several challenges:
- Ensuring Swiss data sovereignty: Swisscom required all customer data to remain within Switzerland, with strict controls ensuring that even AWS could not access, modify, or delete data. To meet these requirements while leveraging cloud benefits, we implemented custom security measures using various AWS security services.
- Handling large volumes of data: the mail platform’s infrastructure has to manage petabytes of data, making storage, backup, and restoration a complex challenge. We designed a scalable cloud solution, capable of handling these vast data volumes efficiently and securely.
- Achieving zero-downtime migration: A seamless transition was critical as any disruption could impact millions of customers. To achieve this, we implemented a dual-operation strategy, where both the old and new mail systems ran in parallel. Customers were gradually migrated, with intelligent routing ensuring that no data was lost and that all services remained operational throughout the transition. Additionally, to enable high availability and efficiently handle millions of user requests, we leveraged AWS’s scalable cloud compute services to dynamically distribute workloads, using modern instance types with built-in memory encryption.
By tackling these challenges head-on, we enabled Swisscom to successfully modernise its Bluewin mail platform while maintaining security, performance, and reliability, setting the stage for future cloud-driven innovations.
“What we appreciated about Zühlke's team was their balance between pragmatism and sustainable software engineering during the project. The team built high-quality and goal-oriented software without losing sight of the target.”
Seamless cloud migration for millions of users
By closely collaborating with Swisscom throughout this major cloud migration, we set a new benchmark for cloud adoption within the organisation. Our expertise was pivotal in both shaping the technical implementation and the broader cloud strategy, helping to establish best practices for future cloud initiatives.
Together, we successfully migrated several petabytes of data and millions of email accounts with zero disruption. As a long-term trusted technology partner, our neutrality and deep understanding of both on-premises and cloud architectures enabled us to provide a comprehensive, unbiased perspective. We were more than just advisors—we were execution partners, ensuring the migration was not only planned effectively but also carried out seamlessly.
‘Using AWS infrastructure services allows our organisation to allocate more resources into efforts that actually drive business and customer value. It also allows us to be highly flexible in scaling infrastructure and resources during peak load times,’ says Matthias, the Product Owner of the Bluewin Mail system.
Beyond delivering a scalable and secure mail platform, we empowered Bluewin mail’s team with the knowledge and confidence to operate and expand their cloud capabilities.
Through close collaboration, hands-on mentoring, and daily knowledge-sharing, we accelerated their internal cloud expertise, laying the foundation for future innovation.
