October 18, 2022

Exchange 2010 to 2016: A Seamless Migration

Executive Summary (Exchange 2010 to 2019)

Company: Foothill Transit
Industry: Public Transportation

Employees: 300

Overview: To upgrade Exchange email servers from Exchange 2010 to 2019 in a virtualized VMware environment at the Foothill Transit headquarters located in West Covina.

Solution: Upgrade to Exchange 2016 and then to Exchange 2019.


Foothill Transit provides community-oriented, environmentally friendly bus service throughout southern California's San Gabriel and Pomona Valleys, including express bus routes to Pasadena and Downtown Los Angeles. Their mission is to be the premier public transit provider committed to safety, courtesy, quality, responsiveness, efficiency, and innovation.


As Microsoft ended support for Exchange 2010 around October 2020, it was time for organizations to start the process of migrating Exchange 2010 to 2019 to upgrade and avoid plethora of security risks. Foothill Transit was one such organization. Moreover, they did not want to go for something different and were confident about Sticking to Microsoft Exchange since the change is transparent for the end-users and the best option in terms of user adoption and training. Exchange 2019 is the latest advanced technology and has many new features. For this purpose, Foothill Transit chose Communication Square, a Microsoft Gold partner, for a seamless transition.

Foothill Transit

To ensure that regular bugs are fixed, security updates are accomplished, and problems are solved, we trusted Communication Square to carry out a hassle-free migration.

Roy Eseyan
Information Technology Manager

Process, Challenges & Solutions

Migrating from Microsoft Exchange 2010 to 2019 is not a task that should be taken lightly. Without proper guidance of experts, such kind of a migration can be unpredictable and unsettling. Therefore, we ensured and used Microsoft Exchange environment calculator and different exchange health scripts, so that the exchange servers are not down for even a single second.

Listed below are the process highlights, as well as some of the challenges posed by this project, along with how our team of Office 365 consultants overcame those challenges and completed the migration smoothly. 

Foothill Transit

Migrating to Exchange Server 2019 seemed to be a very complicated process to us. With Communication Square’s adequate knowledge and technical expertise, we were able to meet the desired outcome and enjoy all the benefits that came with the upgrade.

Gary Castro
IT Specialist
  • Unfortunately, it is not possible to complete an on-premises migration directly from Exchange 2010 to 2019. We first moved to Exchange 2016 and once this migration was completed, we then made the final migration to Exchange 2019.
  • The first thing we faced after the migration was “The maximum number of concurrent server connections has exceeded a per-source limit, closing transmission channel”, so we resolved the issue by increasing the maximum number of connections per source which is twenty by default.
  • Linked mailboxes were not able to sign in after migrating to Exchange 2016; hence, they needed to be converted to user mailboxes.
  • Legacy public folder migration was difficult as compared to Modern public folder migration. That migration needed script by Microsoft, which was not working as per expectation. Consequently, we needed to map the mailboxes manually.
  • Search was not working for some users for the past week.
  • Outlook (on the desktop) version control, Outlooks 2003 2007 and 2010 could not connect to Exchange Server 2016, due to the Autodiscover service that changed how it responded to client requests in 2016\2019 in a way that these older versions of Outlook did not currently understand.
  • Certificate problems – A pivotal issue we encountered just after migration was a certificate error on clients. This related to the fact that Exchange, during installation, registered a service connection point (SCP) in Active Directory for the Autodiscover service, but it registered using the server’s actual domain name and not an alias for the service that we had chosen (and may have used to register and purchase the certificate Foothill was using from a trusted third-party certification authority). We switched this SCP registration for the domain name we used in the certificate so that they matched. As a result, the warning went away.
  • DAG Seeding Failure – This issue was resolved through increasing the Memory and CPU enough to handle the load and rebooted the server for pending reboots for patching.
  • Issues with Namespace – 2016 version requires you to bring individual domains into Exchange in case the domains are in the same Active Directory geographical site

Key Benefits of Exchange 2019 Upgrade

For Foothill Transit, Exchange 2019 helped them improve overall performance and take advantage of the latest storage hardware, including larger disks and solid-state drives (SSDs).

Some Additional features in Exchange server 2019 include the following:

  • Provides support for up to 256 GB of memory and 48 CPU cores.
  • Enables installations on Windows Server Core.
  • Prevents attendees from forwarding meeting invitations.
  • Provides end users with additional Out of Office options.
  • Enables administrators to cancel meetings that were organized by a user who has left the company.

Communication Square LLC

There was huge effort involved in this migration which needed clever planning, resources, hardware, licenses and of course time. Firstly, migrating to Exchange Server 2016 and then to Exchange Server 2019 was a meticulous task plus took a considerate amount of time.

Awais Khalid
Senior Cloud Architect
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