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Get statistics by mailbox provider

GET
/v1/email/stats/mailbox-providers
const { data } = await bird.email.stats.byMailboxProvider({
  from: "2026-05-01",
  to: "2026-05-31",
  limit: 25,
});
for (const row of data) console.log(row.mailbox_provider, row.delivery.delivered);
Response200
{
  "period": {
    "from": "2026-05-01",
    "to": "2026-05-25",
    "data_as_of": "2026-05-25T14:03:10Z"
  },
  "data": [
    {
      "mailbox_provider": "gmail",
      "delivery": {
        "delivered": 8290,
        "bounced": 131,
        "complained": 8,
        "deferred": 4,
        "bounces": {
          "hard": 12410,
          "soft": 14290,
          "admin": 410,
          "block": 920,
          "undetermined": 80,
          "hard_rate": 0.454,
          "soft_rate": 0.523,
          "admin_rate": 0.015,
          "block_rate": 0.0337,
          "undetermined_rate": 0.0029
        },
        "delivery_rate": 0.9844,
        "bounce_rate": 0.0156,
        "complaint_rate": 0.00096
      },
      "engagement": {
        "opens": 5420,
        "opens_non_prefetched": 3210,
        "unique_opens": 3640,
        "unique_opens_non_prefetched": 2480,
        "clicks": 924,
        "unique_clicks": 621,
        "unsubscribes": 12,
        "open_rate": 0.1683,
        "click_rate": 0.0422,
        "unsubscribe_rate": 0.0009
      },
      "latency": {
        "delivery": {
          "p50_ms": 420,
          "p95_ms": 1820,
          "p99_ms": 4920
        },
        "total": {
          "p50_ms": 420,
          "p95_ms": 1820,
          "p99_ms": 4920
        }
      },
      "trend": [
        {
          "bucket": "2026-05-12"
        }
      ]
    }
  ],
  "total": 14,
  "next_cursor": "eyJ2IjoxLCJzIjoiXCIyMDI2LTA1LTI1VDE0OjAzOjEwWlwiIiwiaSI6IjAxOTJmM2IxLTRjN2UtN2EyYi05ZDYxLThmM2E1YzJlN2I0MCJ9",
  "prev_cursor": null,
  "refresh_cursor": "eyJ2IjoxLCJzIjoiXCIyMDI2LTA1LTI1VDE2OjQyOjAxWlwiIiwiaSI6IjAxOTJmM2IxLTllMDQtN2NkMy1iODE3LTJhNmY0ZDFjOGUwOSJ9"
}

Returns delivery, engagement, and deliverability counts for the requested period, grouped by recipient mailbox provider, for example gmail, yahoo, microsoft, or apple. Use it to compare how each major inbox provider treats your mail, for example to spot a delivered-rate dip or a complaint spike at one provider before it spreads. For a per-region split within a provider, use the mailbox-provider-region breakdown.

A recipient's mailbox provider is only known once the receiving mail system reports an outcome, so this breakdown covers the delivery stage onward. Accepted, processed, and rejected counts and processing latency are not included. Rows are computed against event time rather than send time.

Rows are ranked by the sort metric, delivered by default, and paginated with the requested limit (50 by default, 200 at most). The window can span at most 365 days. Ask for more and you get a 422.

Query Parameters

starting_afterstring

Cursor from the next_cursor field of a previous list response. Returns items immediately after the cursor position in the current sort order.

ending_beforestring

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.

fromstring

Start date (inclusive) in YYYY-MM-DD, interpreted as a calendar day in timezone (a UTC day when timezone is omitted). It defaults to 30 days before to when you leave it out. When include_trend=true and trend_grain=hourly, that default tightens to 29 days before to instead, so the defaulted window still fits inside the 720-hour trend cap.

tostring

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.

timezonestring

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.

categorystring

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.

sortstring

Metric to rank rows by, applied descending. Any count or rate in the response can be used. A row whose rate is undefined because its denominator is zero sorts last. It defaults to delivered. processed, rejected, and oob_bounces are not part of this breakdown's rows, so they are not sortable here.

Possible values: delivered, bounced, complained, deferred, bounces.hard, bounces.soft, bounces.admin, bounces.block, bounces.undetermined, opens, opens_non_prefetched, unique_opens, unique_opens_non_prefetched, clicks, unique_clicks, unsubscribes, delivery_rate, bounce_rate, complaint_rate, open_rate, click_rate, unsubscribe_rate, bounces.hard_rate, bounces.soft_rate, bounces.admin_rate, bounces.block_rate, bounces.undetermined_rate

limitinteger

Maximum number of mailbox-provider rows to return, ranked by the sort field descending.

include_trendboolean

When true, each row also gets a trend array: a short per-bucket series showing that provider's delivery and engagement rates over the window. This only works when limit is 50 or fewer and the window is at most 90 days for trend_grain=daily or 720 hours for trend_grain=hourly. Ask for more and you get a 422. When you leave from out and use trend_grain=hourly, the default window tightens to 29 days before to (720 hours total), so a request built entirely from defaults always fits inside the cap.

trend_grainstring

Bucket grain for the trend series. Has no effect unless include_trend=true.

Possible values: daily, hourly

Response Payload

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.

Show child attributes
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

Mailbox-provider breakdown rows, ranked by the sort metric (default delivered) descending. Empty when no eligible activity occurred in the period.

Show child attributes
data.mailbox_provider
string
required

The recipient mailbox provider this row aggregates, as a lowercase classifier such as gmail, yahoo, microsoft, or apple. New classifiers may be added over time.

data.delivery
object
required
Show child attributes
data.delivery.delivered
integer
required

Distinct recipients whose message the receiving mail server accepted.

data.delivery.bounced
integer
required

Distinct recipients whose delivery failed. Approximately the sum of the five bounces.* sub-counts (hard, soft, admin, block, undetermined); the totals are computed independently so they may differ slightly at the approximation error.

data.delivery.complained
integer
required

Distinct recipients who reported the message as spam.

data.delivery.deferred
integer
required

Distinct recipients in transient delivery deferral that is still being retried.

data.delivery.bounces
object
required
Show child attributes
data.delivery.bounces.hard
integer
required

Distinct recipients with a permanent delivery failure (invalid address or non-existent domain).

data.delivery.bounces.soft
integer
required

Distinct recipients with a transient delivery failure (mailbox full or server temporarily unavailable).

data.delivery.bounces.admin
integer
required

Distinct recipients refused by a policy at the receiving end, such as relaying denied or a blocklisted domain.

data.delivery.bounces.block
integer
required

Distinct recipients bounced because the receiving mail server blocked the sending IP for reputation reasons.

data.delivery.bounces.undetermined
integer
required

Distinct recipients bounced where the receiving server's response did not allow precise classification.

data.delivery.bounces.hard_rate
nullable number
required

Fraction of bounced recipients that hard bounced, computed as hard / bounced. Null when bounced is zero.

data.delivery.bounces.soft_rate
nullable number
required

Fraction of bounced recipients that soft bounced, computed as soft / bounced. Null when bounced is zero.

data.delivery.bounces.admin_rate
nullable number
required

Fraction of bounced recipients that admin bounced, computed as admin / bounced. Null when bounced is zero.

data.delivery.bounces.block_rate
nullable number
required

Fraction of bounced recipients that block bounced, computed as block / bounced. Null when bounced is zero.

data.delivery.bounces.undetermined_rate
nullable number
required

Fraction of bounced recipients with undetermined classification, computed as undetermined / bounced. Null when bounced is zero.

data.delivery.delivery_rate
nullable number
required

Share of attempted recipients on this mailbox provider that were delivered, computed as delivered / (delivered + bounced). Null when delivered + bounced is zero (no attempts).

data.delivery.bounce_rate
nullable number
required

Share of attempted recipients on this mailbox provider that bounced, computed as bounced / (delivered + bounced). Null when delivered + bounced is zero (no attempts).

data.delivery.complaint_rate
nullable number
required

Share of delivered recipients on this mailbox provider who reported the message as spam, computed as complained / delivered. Null when delivered is zero.

data.engagement
object
required
Show child attributes
data.engagement.opens
integer
required

Distinct open events, counting repeat opens from the same recipient and opens auto-fetched by inbox privacy features (such as Apple Mail Privacy Protection and the Gmail image proxy).

data.engagement.opens_non_prefetched
integer
required

Distinct open events excluding those auto-fetched by inbox privacy features. Same event-counting semantics as opens (repeat opens from the same recipient count separately), with prefetched opens removed.

data.engagement.unique_opens
integer
required

Distinct recipients who opened at least once, including opens auto-fetched by inbox privacy features.

data.engagement.unique_opens_non_prefetched
integer
required

Distinct recipients who opened at least once, excluding opens auto-fetched by inbox privacy features. This is the numerator used for open rate, so iOS-heavy audiences (Apple Mail Privacy Protection and similar) do not inflate it.

data.engagement.clicks
integer
required

Distinct click events, counting repeat clicks from the same recipient.

data.engagement.unique_clicks
integer
required

Distinct recipients who clicked at least once.

data.engagement.unsubscribes
integer
required

Distinct unsubscribe events, recorded via the list-unsubscribe header or the footer link.

data.engagement.open_rate
nullable number
required

Distinct non-prefetched openers relative to effectively delivered recipients in the same scope, computed as unique_opens_non_prefetched / delivery.effective_delivered; on rows without an effective_delivered field (the mailbox-provider breakdowns) the denominator equals delivery.delivered. The numerator excludes opens auto-fetched by inbox privacy features. Opens are attributed by event time, so engagement earned by earlier deliveries can push the rate above 1. Null when the denominator is zero.

data.engagement.click_rate
nullable number
required

Distinct clickers relative to effectively delivered recipients in the same scope, computed as unique_clicks / delivery.effective_delivered (delivery.delivered on rows without an effective_delivered field). Clicks are attributed by event time, so engagement earned by earlier deliveries can push the rate above 1. Null when the denominator is zero.

data.engagement.unsubscribe_rate
nullable number
required

Unsubscribe events relative to effectively delivered recipients in the same scope, computed as unsubscribes / delivery.effective_delivered (delivery.delivered on rows without an effective_delivered field). Unsubscribes are attributed by event time, so the rate can exceed 1. Null when the denominator is zero.

data.latency
object
required
Show child attributes
data.latency.delivery
object
required

Approximate p50, p95, and p99 latency percentiles in milliseconds for one latency family over the bucket. All three are null when no qualifying event contributed a measurement.

Show child attributes
data.latency.delivery.p50_ms
nullable integer
required

Median (50th percentile) latency in milliseconds. Null when no qualifying event contributed a measurement.

data.latency.delivery.p95_ms
nullable integer
required

95th percentile latency in milliseconds. Null when no qualifying event contributed a measurement.

data.latency.delivery.p99_ms
nullable integer
required

99th percentile latency in milliseconds. Null when no qualifying event contributed a measurement.

data.latency.total
object
required

Approximate p50, p95, and p99 latency percentiles in milliseconds for one latency family over the bucket. All three are null when no qualifying event contributed a measurement.

Show child attributes
data.latency.total.p50_ms
nullable integer
required

Median (50th percentile) latency in milliseconds. Null when no qualifying event contributed a measurement.

data.latency.total.p95_ms
nullable integer
required

95th percentile latency in milliseconds. Null when no qualifying event contributed a measurement.

data.latency.total.p99_ms
nullable integer
required

99th percentile latency in milliseconds. Null when no qualifying event contributed a measurement.

data.trend
array of object

Per-bucket rate series for this mailbox provider over the window. Present only when include_trend=true.

Show child attributes
data.trend.bucket
string
required

The day (YYYY-MM-DD) or hour (ISO 8601, on the hour) this point covers, matching the requested trend_grain.

data.trend.delivered
integer
required

Delivered recipients in this bucket.

data.trend.bounced
integer
required

Bounced recipients in this bucket.

data.trend.delivery_rate
nullable number
required

Delivery rate for this bucket, as a fraction. Null when nothing was delivered or bounced.

data.trend.bounce_rate
nullable number
required

Bounce rate for this bucket, as a fraction. Null when nothing was delivered or bounced.

data.trend.complaint_rate
nullable number
required

Complaint rate for this bucket, as a fraction. Event-time attribution can push it above 1 when complaints outrun the bucket's deliveries. Null when nothing was delivered in the bucket. On a sending-IP row complaints are not attributed to the IP, so this reads 0 in buckets that had deliveries and null in buckets that had none.

data.trend.open_rate
nullable number
required

Open rate for this bucket, as a fraction. Event-time attribution can push it above 1 when opens outrun the bucket's deliveries. Null when nothing was delivered in the bucket. On a sending-IP row engagement is not attributed to the IP, so this reads 0 in buckets that had deliveries and null in buckets that had none.

data.trend.click_rate
nullable number
required

Click rate for this bucket, as a fraction. Event-time attribution can push it above 1 when clicks outrun the bucket's deliveries. Null when nothing was delivered in the bucket. On a sending-IP row engagement is not attributed to the IP, so this reads 0 in buckets that had deliveries and null in buckets that had none.

total
integer
required

Total number of distinct mailbox providers 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

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