Domino to Exchange Coexistence: Is It Really Necessary?

There’s no question that we’re in the midst of an extreme market shift from IBM/Lotus Notes and Domino to Microsoft Exchange. As a company with over 20 years of migration experience (originally with clients migrating to Domino), we at Binary Tree advise our customers on best practices for smooth transitions and any situations that require coexistence.

First, realize that every Notes environment is different. Every enterprise has its own best practices, standards, custom applications and interpretation of Domino capabilities, so you can’t just “plug in” a coexistence product and magically have a seamless migration appear. You will likely need coexistence to provide your users with full messaging functionality unless you are a small company. If you are just migrating a small number of email boxes, typically all on the same day or over the same weekend, and you have no Notes applications that send email directly to your users, your organization likely does not need to setup coexistence between the email platforms.

Next, let’s focus on enterprise migrations that are more complex. Larger organizations moving from Domino to Exchange typically need to do so over a period of time. With some of the discrepancies that exist between Domino and Exchange, these types of phased approaches (also referred to as staged migrations) require special attention to calendars, free/busy access, directory synchronization, and message threading. More often than not, there are also legacy Domino-based applications that were originally designed to interact with a Lotus Notes client. These may not work at all in Exchange, and require some additional pre-planning and execution time to ensure everything works.

CMT for Coexistence Diagram

A classic example of a Domino-based app is an expense reporting system—one that allow users to fill out a form via email and have their managers approve or deny the expense with the click of a button in that email. That button, called an “embedded Notes element,” is no simple matter to migrate for, say thousands of users. It expects a Notes client on the receiving end. If I were to send this email via Exchange, the email is converted from Notes Rich Text to MIME and there’s nothing to convert those embedded Notes Elements. This is a situation where coexistence is absolutely necessary, and essential to user satisfaction post-migration.

Here’s how…and the wow!
Using the same router extension technology that’s used to scan Domino email for viruses, Binary Tree’s Coexistence product will identify emails containing any element that won’t translate to MIME. Any email containing embedded Notes elements, hot spots (dialog boxes), or computed text elements (where you send an email to the entire company, but it’s personalized) can be problematic. And here’s the wow: with Binary Tree’s ZApp (Zero-touch Application remediation), the email will be stored securely on the Domino Coexistence server; the Outlook user will receive an email with a link back to that specific document; and that link will allow them to open it in Lotus Notes—seamlessly and without requiring the organization to change or modify their existing custom Notes applications.

Planning for Coexistence
If you have determined that you do need to coexist with Domino and Exchange during your migration, your first order of business is to research, identify, and verify what’s in Domino so that you can properly plan the coexistence. For example, we’ve had projects with 1,200 people and 800 applications. In a situation like that, we need to understand how many of those applications are being used and which ones are only repositories. We had another client with 30,000 employees and 80,000 groups – and half of their groups didn’t even have members in them! These factors and many more can influence how you approach and design for coexistence.

Here are some key preliminary items you’ll need to confirm first:

  • The number of users to be migrated
  • The amount of data to be migrated
  • The target platform environment; Are you moving to an on-premises Exchange environment, to a cloud/hosted infrastructure, or to a hybrid deployment with some users on-premises and some in the cloud?
  • The timeframe for the project
  • The existence of applications, like the expense reporting system described above, that will send “embedded Notes elements” to end users


And when you’re ready to dig deeper, here’s more of what you’ll need to know about your existing environment to plan for coexistence:

  • Number of users, databases, rooms and resources within the Domino Directory
  • The size of the mail databases—largest, smallest, and average size
  • Storage of attachments in DAOS (Domino Object and Attachment Service)—while users can open an attachment in one place (eliminating of lot of storage), you still have to migrate that data
  • Identifying applications that interact with the end user via email, and the details of those messages from a content perspective
  • Customizations to the mail template – Exchange doesn’t provide this capability, and those customizations may not be relevant in Exchange
  • All third-party Domino add-ins, like fax services, or other systems that send SMTP Mail to Domino
  • All items that have and do not have SMTP addresses (such as groups, rooms, resources, mail-in-databases)


Takeaway: Having the answers to these and other questions and understanding the specific differences between Domino and Exchange (in conjunction with email and calendaring) will help an organization make the determination of whether or not coexistence is required. If Coexistence is for you, Binary Tree has the experience, expertise, technology and methodologies to help. For more information on our solutions for coexistence, attend an upcoming occurrence of our SMART Solutions for Exchange to Notes Migrations webinar.