# API compatibility notes
## Token model
- Endpoints that require `X-Postmark-Server-Token` should be used with `PostmarkClient.server_token`.
- Endpoints that require `X-Postmark-Account-Token` should be used with `PostmarkClient.account_token`.
- The client can carry both; endpoint docs in `docs/api/postmark-endpoints.md` show expected token type.
## Deprecated endpoints policy
- Sender Signature deprecated endpoints are intentionally excluded:
- `POST /senders/{id}/verifyspf`
- `POST /senders/{id}/requestnewdkim`
- Preferred replacement for DKIM operations is Domains API (`/domains/{id}/rotatedkim`).
## Field naming and casing
- API payloads are modeled with Postmark PascalCase keys through serde renames.
- Paths are matched to docs exactly (including lowercase segments like `verifyspf`, `rotatedkim`).
## Forward-compat strategy
- Unknown fields from Postmark are ignored by serde by default.
- Dynamic-key stats endpoints (`emailclients`, `browserfamilies`) are represented with a flattened map payload in response structs.