Built for Enterprise Scale

This solution operates on a continuous, near-real-time delta sync cycle. When an item (email, calendar event, contact, file) is created or modified in the primary environment, the change is picked up and replicated to the standby environment within minutes, depending on your configured polling intervals, your specific environment, and API throttling limits.

For Self-Hosted: The environment (on-premises or private cloud VM) needs network connectivity to both source and target environments, and service accounts with appropriate impersonation or application permissions (OAuth2/Graph API for M365 and SharePoint; impersonation roles for Exchange).

For SaaS: No local infrastructure is required, but deployment requires granting secure API permissions via standard OAuth 2.0 admin consent for both your primary and standby tenants.

Syncing mail can mean one of two things:

1. Synchronize one account from the server to the client – This means getting the email items, namely the messages or calendar items, from the server to client devices.
2. Synchronize multiple email accounts - This is the case covered by CB Exchange Server Sync: you have two e-mail accounts, and synchronization will allow you to choose one of them as a “origin account” and the other one as the "target account". All the information is automatically copied from the origin to the target account. This way you can check all of your email messages, calendar items and more from a single location. You can also do the same bidirectionally and for multiple pairs of accounts.For more details, check this article.

You can set the frequency of synchronization by defining Polling Interval inside the SaaS dashboard.
Polling Interval determines how often the synchronization service checks for changes to perform since the last synchronization on the Exchange Server.

PLEASE NOTE: A shorter interval results in faster and more precise synchronization. If you have chosen a SaaS deployment, beware that a shorter interval increases traffic.

Yes. Moreover, migrating mailboxes is great with CB Exchange Server Sync, as you can work with both accounts in parallel and do it in iterations or batches if needed. 

Yes. CB Exchange Server Sync can synchronize:

• Public folders
  Public folders can also be mapped to normal user mailboxes if needed, and cross-tenant or cross-domain scenarios are supported.
  

• Shared mailboxes
  The setup is similar to standard mailboxes: you specify the source and target folders in the sync configuration and assign the service account the necessary access rights. 

CB Exchange Server Sync covers almost all mailbox content, including emails, calendar events, contacts, tasks, and attachments.
There are a few expected exclusions:

• Exceptionally large individual items that might not be supported by the destination Exchange Server 
• Recoverable Items / Deleted Items versions are not included, as they are outside the normal mailbox scope. You can, however, configure the solution to take into account your retention policies.

In practice, these exceptions do not affect day-to-day mailbox synchronization.

You can choose between two models:

• Subscription license (per sync pair, per month or year) – best for flexibility and OPEX budgeting.
• Perpetual license (one-time purchase per sync pair) – best for long-term ownership and CAPEX budgeting.

License activation is straightforward: after installation, you request a license, and then activate it. 

For successful synchronization, it is essential to know the exact Exchange Server version you have. You can find it by:

• Asking your IT administrator or hosting provider – They can quickly confirm whether you use on-premises Exchange (e.g., 2016, 2019) or Microsoft 365 Exchange Online.

• Following Microsoft’s official instructions – Use their guide to locate and match your server’s build number with the correct version: Microsoft Support

Yes, you can. CB Exchange Server Sync can operate even in strictly isolated or classified environments when paired with hardware data diodes, allowing you to safely synchronize Exchange data in a controlled, one-way direction.

This setup is ideal for organizations in defense, government, or highly regulated industries that require complete separation between systems. It ensures data integrity and confidentiality while still keeping calendars, contacts, and tasks aligned across environments.

The same principle can also scale to more advanced configurations, as you can see on the specific page CB Exchange Server Secure Sync with Data Diodes