Initial History Scans
When first connecting mailboxes, the OPE must process historical emails and meetings.
The OPE can be configured to run once per day or multiple times per day, depending on how your server is set up.
Processing speed depends on the number of mailboxes, the amount of history (e.g., 1 year vs. 10 years), and available server cores. More cores = faster processing.
Example: 100 mailboxes with 1 year of history on a 4-core server could take 2–11 days to process, depending on mailbox activity.
Daily Ongoing Scans
Once history processing is complete, daily scans become much lighter and faster.
For ongoing scanning, the OPE only processes new data (emails and meetings from the past day).
Typically, 1x per day is sufficient to keep all mailboxes up to date.
This means servers can often be downsized after history processing is complete, reducing resource usage and cost.
Resource Planning
History Scans: Allocate enough cores for initial throughput (e.g., 4+ cores for medium deployments).
Daily Scans: 2 cores minimum; each core can usually handle ~200 mailboxes.
RAM: Minimum 2 GB of RAM per core.
⚠️ Performance gains diminish after ~24 cores.
Key Takeaway
During initial history scanning, expect higher server demand and longer runtimes. After history is complete, daily scans are lightweight, can run once per day, and allow you to optimize (or downsize) your server resources.