Integration
CYNC writes Entra ID users into Exchange Online mailbox contact folders. Once synced, the Global Address List appears as native contacts on every device — iPhone, Android, Outlook desktop, Outlook mobile, and Teams.
CYNC queries Microsoft Graph /users with delta tokens to fetch only the users that changed since the last run. Source filters narrow the list to exactly the users you want exposed (e.g. enabled employees in a specific group).
Target filters select which mailboxes receive the contact set — all licensed users, members of a department, or a custom group. CYNC processes target mailboxes in parallel with tunable concurrency.
For each target mailbox, CYNC writes contacts into a dedicated folder using POST /users/{id}/contactFolders/{id}/contacts. Existing contacts are matched by Graph Open Extension correlation IDs to avoid duplicates.
Exchange Online pushes contacts via ActiveSync to iPhone and Android, via MAPI to Outlook desktop, and via Graph to Outlook mobile and Teams. No device-side configuration. No MDM profile.
Once CYNC writes contacts to Exchange Online, every Microsoft 365 client picks them up automatically.
| Client / device | Sync protocol | Result |
|---|---|---|
| iPhone (Mail app) | Exchange ActiveSync | Native — all contacts |
| Android (Gmail / Outlook) | Exchange ActiveSync / Graph | Native — all contacts |
| Outlook for Windows / Mac | MAPI / Exchange Web Services | Native — Other Contacts folder |
| Outlook on the web | Microsoft Graph | Native — appears in directory |
| Outlook mobile (iOS/Android) | Microsoft Graph | Native — searchable everywhere |
| Microsoft Teams | Microsoft Graph | Caller ID + chat directory |
CYNC targets Exchange Online (Microsoft 365). For pure Exchange on-premises environments, the GAL is already visible to Outlook clients but not always to mobile devices — CYNC is not designed for that scenario. Hybrid customers can use CYNC for the Exchange Online side of the deployment.
Exchange Online contact folders sync to mobile devices via Exchange ActiveSync (the same protocol that delivers email and calendar). When CYNC writes contacts to a user's mailbox, ActiveSync replicates them to every device connected to that mailbox — typically within minutes, with no device-side action required.
By default, CYNC creates and maintains a folder named 'CYNC' under each user's contact root. You can rename or relocate the folder in CYNC's settings. The folder name is configurable per deployment.
No. CYNC only manages contacts inside its own folder, and uses Graph Open Extensions to identify CYNC-owned records. User-created contacts in the default Contacts folder are never touched.
CYNC focuses on user mailboxes. For shared and resource mailboxes, you can include them in the target filter — Exchange Online treats them as standard mailboxes via Graph.
Yes. CYNC honors Microsoft Graph 429 Retry-After responses and applies exponential backoff. Per-tenant concurrency is tunable in the dashboard so large rollouts don't impact other Microsoft 365 services.
When a contact's mobile and business numbers are written into the contact card, the iPhone and Android dialers use that data for inbound caller ID — even when the device is offline. This is one of the most common reasons IT teams deploy contact sync.
Free for 10 users per tenant — no credit card, no time limit.