01
Scope
Choose the folders that belong in the product
Message delta operates per folder. Discover folders, store their Graph IDs, and maintain separate state for Inbox, Sent Items, custom folders, or shared mailbox folders selected by the product.
Email
ResearchEmail engineering guide
Synchronizing Outlook mail with Microsoft Graph delta
Graph delta provides durable folder-level change tracking when the client treats next and delta links as opaque state and pairs notifications with reconciliation.
Research surface only. This guide documents architecture and evaluation criteria; it does not describe a released DewEngine connector.
02
Initial round
Follow every next link before recording the checkpoint
Begin at the folder's messages/delta endpoint, apply each page, and follow the exact @odata.nextLink until Graph returns @odata.deltaLink. An interrupted round must resume from its saved next link or restart safely.
- Per-folder worker state
- Opaque next link
- Transactional page application
- Final delta link
03
Incremental round
Apply creates, updates, and removals idempotently
Replay the stored delta link, upsert current messages, process removal markers, and commit the new link only after the changes succeed. Keep provider change keys for conditional updates where the workflow writes back.
04
Near real time
Renew Graph subscriptions and reconcile after each signal
Change notifications can wake the folder worker, but subscriptions expire and notification delivery is not the local source of truth. Renew before expiry, validate notifications, and run delta after gaps or lifecycle warnings.
- Endpoint validation
- Subscription renewal
- Duplicate notification tolerance
- Periodic delta backstop
Questions
Before you build.
Why is Microsoft Graph email delta per folder?+
That is the provider's documented message change boundary. A product that synchronizes several folders must coordinate several independent delta streams.
Does a change notification eliminate the need for delta query?+
No. Delta query reconciles the authoritative set of additions, updates, and deletions; the notification is primarily a trigger to perform that work promptly.
Can I use DewEngine's email connectors today?+
Not yet. Gmail, Microsoft Graph, and IMAP/SMTP connectors are planned. This guide documents the intended architecture and the provider requirements a production release must satisfy.
Build with us
Does this match the workflow your users need?
DewEngine is in development. Real use cases decide what ships first.