Server connections

Connection configuration and features

CodeTwo Backup is designed to work with both Exchange Server On-premises and Office 365 plans with Exchange Online. In both cases the software uses the server’s domain administrator account with impersonation permissions granted, to access mailboxes data via the Exchange Web Services (EWS). Office 365 connection configuration is pretty straightforward and Exchange On-premises connection can be configured automatically using Exchange Server’s Autodiscover as well as manually, allowing administrators to point at the right server using server’s name or even just an IP address.

The CodeTwo Backup user can define multiple connections with built-in wizard to allow performing backup and restore jobs to and from many different servers. The software automatically handles any resource conflicts, i.e. if multiple jobs are to be executed against the same mailbox, the same connection is about to be used to run a few different jobs or the same storage will be accessed by more than one job at once, the software’s engine will queue those jobs properly to avoid data corruption or looping. Non-converging jobs can be ran simultaneously.

All connection details configured in the software are kept safe encrypted and accessing previously configured connections requires entering the password. This allows the main administrator to configure the software and then to delegate running the software to other, less privileged admins without the risk of them accessing sensitive credentials. However, as much as we agree with the “safety first” idea, the convenience of use is also important. This is why once provided password keeps the connection details unlocked until the user closes the current Administration Panel session. Also, if the currently logged on user is the same as the one whose credentials are used within the connection details, entering a password to access this connection configuration will not be required.

Connection speed

CodeTwo puts reliability of the backup process over its speed. There is a specially crafted, rather complex algorithm implemented that is constantly running as backup jobs are active, which makes sure that current process speed is optimal when it comes to the backup safety. The algorithm constantly analyzes the backup process performance ratings and marshals the number of concurrent connections. More of these are automatically allowed if the connection speed is fast and reliable enough and if the Exchange Server responds to software’s queries consistently in a timely manner. Connection slots are automatically dropped if the software notices any transfer issues.


For the backup process safety, manually overriding the connection slots management mechanism is deliberately prohibited.

Disallowing user's tweaks, as well as implementing the above described algorithm - that can be possibly considered overcautious by some, are to make sure the software does not lose anything in the process. During the CodeTwo Backup development and the software internal and external beta testing, we have noticed that too liberal approach to backup parameters management (e.g. connection slots numbers, items batch sizes, bandwidth speed usage) resulted in the Exchange Server connection timeouts. When it comes to data backup the process reliability is crucial and connection timeouts that can lead to data loss or corruption are unacceptable, hence the focus on process consistency and stability rather than on maximizing backup speed.

During the software development and testing data backup speed varying from ~700 MB per hour to more than 6 GB per hour was observed. Aside from some obvious reasons, for example the Internet connection speed, such results scatter is caused by the mailboxes characteristics. The backup process is considerably faster for bigger items (e.g. lots of emails with big attachments or embedded images). Backing up smaller items (e.g. simple text-only emails) engages the Exchange Server more and requires setting up more connections between a user's computer and the Exchange Server machine, therefore lower backup process performance can be expected.

In some cases, users may notice that the actual backed up or restored data transfer speed is considerably slower than their network bandwidth. This is because the whole process speed depends on multiple factors, e.g. local network and Internet connection speed, physical location of the mailbox server, servers’ throttling settings, Exchange Server performance. Be aware that while you can customize your Exchange On-premises throttling settings, doing the same for Exchange Online is not possible due to Microsoft’s policy.


Exchange Online users should also note that purchasing Office 365 subscription in one geographic region does not necessarily mean their data is actually stored within the region. As your mailboxes might be kept in datacenters located on a different continent you need to take under consideration the fact that a network connection speed bottleneck can theoretically occur between Microsoft's servers. Also, the connection latency to such remote mailboxes may be higher and affect the backup process speed.

Be aware, you might not be able to notice that when accessing mailboxes via OWA365 or Outlook as the Office 365 CAS servers may actually be hosted within your region while the mailbox role servers might be somewhere else. Please consult this Microsoft legal notice on the data country/region storage policy or contact Microsoft's support to find out where your Exchange Online mailbox stores are physically located.

In the case of backing up process speed issues please consult with our Knowledge Base article on that.

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