--- title: "Get bounces by SMTP error code" canonical: "https://bird.com/docs/api/reference/get-email-stats-by-bounce-code" --- # Get bounces by SMTP error code `GET /v1/email/stats/bounce-codes` Returns bounce counts for the requested period, grouped by the SMTP error code the receiving mail server returned. It answers the question of which SMTP responses are driving your bounces. Each row reports how many recipients bounced with that code, plus the hard, soft, admin, block, and undetermined split for that code. This failure-only breakdown omits delivered, open, click, and rate fields because bounce codes occur only on bounce events. Rows are ranked by the `sort` metric, `bounced` by default, and paginated with the requested `limit` (50 by default, 200 at most). They are computed against event time rather than send time. The window can span at most 365 days. Ask for more and you get a `422`. ## Code samples **TypeScript** ```ts const { data } = await bird.email.stats.byBounceCode({ from: "2026-05-01", to: "2026-05-31", sort: "bounced", limit: 25, }); for (const row of data) console.log(row.smtp_error_code, row.bounced); ``` Examples: [TypeScript](/docs/api/reference/get-email-stats-by-bounce-code.ts.md) · [Python](/docs/api/reference/get-email-stats-by-bounce-code.py.md) · [Go](/docs/api/reference/get-email-stats-by-bounce-code.go.md) · [PHP](/docs/api/reference/get-email-stats-by-bounce-code.php.md) · [CLI](/docs/api/reference/get-email-stats-by-bounce-code.cli.md) · [MCP](/docs/api/reference/get-email-stats-by-bounce-code.mcp.md) · [cURL](/docs/api/reference/get-email-stats-by-bounce-code.curl.md) ## Example response `200` ```json { "period": { "from": "2026-05-01", "to": "2026-05-25", "data_as_of": "2026-05-25T14:03:10Z" }, "data": [ { "smtp_error_code": "5.1.1", "bounced": 1240, "bounces": { "hard": 42, "soft": 48, "admin": 4, "block": 6, "undetermined": 1 } } ], "total": 17, "next_cursor": "eyJ2IjoxLCJzIjoiXCIyMDI2LTA1LTI1VDE0OjAzOjEwWlwiIiwiaSI6IjAxOTJmM2IxLTRjN2UtN2EyYi05ZDYxLThmM2E1YzJlN2I0MCJ9", "prev_cursor": null, "refresh_cursor": "eyJ2IjoxLCJzIjoiXCIyMDI2LTA1LTI1VDE2OjQyOjAxWlwiIiwiaSI6IjAxOTJmM2IxLTllMDQtN2NkMy1iODE3LTJhNmY0ZDFjOGUwOSJ9" } ``` ## Query parameters - `starting_after` (string): Cursor from the `next_cursor` field of a previous list response. Returns items immediately after the cursor position in the current sort order. - `ending_before` (string): Cursor from the `prev_cursor` or `refresh_cursor` field of a previous list response. Returns items immediately before the cursor position in the current sort order. `prev_cursor` returns the preceding page. `refresh_cursor` anchors at the first row of that response, which on a newest-first sort is how to fetch the items that have appeared since. - `from` (string): Start date (inclusive) in `YYYY-MM-DD`, interpreted as a calendar day in `timezone` (a UTC day when `timezone` is omitted). Defaults to 30 days before `to` when omitted. - `to` (string): End date (inclusive) in `YYYY-MM-DD`, interpreted as a calendar day in `timezone` (a UTC day when `timezone` is omitted). Defaults to today in that timezone when omitted. Window may not exceed 365 days. - `timezone` (string): IANA timezone identifier used to group statistics, for example `Asia/Kathmandu`. The default is UTC. Day and hour boundaries, including the default window when `from` and `to` are omitted, follow this timezone. When this parameter is set, pass `from` and `to` as calendar days or `Z` instants instead of timestamps with explicit UTC offsets. - `category` (string): Not supported on breakdown endpoints. Supplying it returns `422`. To compare categories, use `GET /v1/email/stats/categories`. The summary, daily, and hourly statistics accept `category` as a filter. - `sort` (string) Metric to rank rows by, applied descending. It defaults to `bounced`. Only the bounce counts are sortable here, because this breakdown has no rate fields. Possible values: `bounced`, `bounces.hard`, `bounces.soft`, `bounces.admin`, `bounces.block`, `bounces.undetermined` - `limit` (integer): Maximum number of bounce-code rows to return, ranked by the `sort` field descending. ## Response body - `period` (object, required): The date range the response covers (echoed back from the request), plus `data_as_of`, the freshness boundary the data is current to. - `period.from` (string, required): Inclusive start date the response covers (YYYY-MM-DD). - `period.to` (string, required): Inclusive end date the response covers (YYYY-MM-DD). - `period.data_as_of` (nullable string): The instant the statistics in this response are current to: events recorded up to roughly this time are reflected, while more recent events may not be yet. Statistics are served from a rolling aggregation that refreshes every few seconds, so a response reflects data from up to a few seconds ago. Use this field to label data freshness (for example "as of 14:03") rather than assuming the numbers are to-the-second. Null when the freshness boundary is not being reported. - `data` (array of object, required): Bounce-code breakdown rows, ranked by the `sort` metric (default `bounced`) descending. Empty when no bounces occurred in the period. - `data.smtp_error_code` (string, required): The SMTP error code the receiving mail server returned for these bounces, as reported by that server (for example `5.1.1` for an unknown recipient, `4.2.2` for a full mailbox). The form varies by server, and the set of codes is open. - `data.bounced` (integer, required): Distinct recipients whose delivery failed with this SMTP status code, approximately equal to the sum of the five `bounces.*` sub-counts. The two are computed independently, so they can differ slightly because of approximation. - `data.bounces` (object, required) - `data.bounces.hard` (integer, required): Distinct recipients with a permanent delivery failure (invalid address or non-existent domain). The address is automatically added to the suppression list. - `data.bounces.soft` (integer, required): Distinct recipients with a transient delivery failure (mailbox full or server temporarily unavailable). Delivery was retried. - `data.bounces.admin` (integer, required): Distinct recipients refused by a policy at the receiving end, such as relaying denied or a blocklisted domain. Fix these by changing your content or sender configuration. Cleaning the recipient list does not usually help. - `data.bounces.block` (integer, required): Distinct recipients bounced because the receiving mail server blocked the sending IP for reputation reasons (mail block, spam block, spam content). Triage usually focuses on IP reputation and sending volume. - `data.bounces.undetermined` (integer, required): Distinct recipients bounced where the receiving server's response did not allow precise classification. - `total` (integer, required): Total number of distinct SMTP error codes with activity in the period, regardless of `limit`. Pass `next_cursor` as `starting_after` to request the next page. - `next_cursor` (nullable string, required): Cursor for the next page. Pass back as `starting_after` to advance forward. `null` when no next page exists. - `prev_cursor` (nullable string, required): Cursor for the previous page. Pass back as `ending_before` to step backward. `null` when no previous page exists. - `refresh_cursor` (nullable string, required): Refresh anchor, the first row of this response. Pass back as `ending_before` to fetch what precedes it in the current sort order. On a newest-first sort those are the items that have appeared since; on any other sort they are the items that sort earlier, so refreshing such a list means re-fetching it instead. Non-`null` whenever `data` is non-empty; `null` only on an empty page. Distinct from `prev_cursor`. ## Related resources - [What is click-through rate for email and SMS?](/explained/engagement/what-is-click-through-rate) (answer) - [Email analytics](/email-api/features/analytics) (product) - [Email metrics](/docs/guides/email/tracking-and-metrics) (docs) [Get an implementation brief](/learn/workspace?topic=email-metrics)