Returns the mailbox's sent and received email statistics over a time window: a period-wide summary plus a bucketed series. Sent-mail metrics carry the same delivery, engagement, and latency breakdowns as the email stats endpoints; `received` counts mail that arrived at the mailbox. Rows are bucketed by event time, not send time — engagement received during the period for messages sent earlier is included. Statistics start when the mailbox starts sending and receiving; the mailbox's all-time `message_count` and `thread_count` live on the mailbox resource itself. `from` and `to` accept either calendar days (YYYY-MM-DD, `day` granularity only) or RFC 3339 instants (`hour` granularity only). Both bounds must use the same form. Window caps depend on `granularity`: 365 days at `day`, 30 days at `hour`. Set `timezone` to report in a local zone instead of UTC. Inclusive start of the window: a calendar day (YYYY-MM-DD, `day` granularity only) or an RFC 3339 instant rounded down to the hour (`hour` granularity only). Interpreted in `timezone`, or in UTC when `timezone` is omitted. A numeric UTC offset is rejected when `timezone` is set; use a calendar day or a `Z` (UTC) instant. Must use the same form as `to`. Defaults to 30 days before `to` at `day` granularity and 7 days before `to` at `hour`, when omitted. Inclusive end of the window: a calendar day (YYYY-MM-DD, `day` granularity only) or an RFC 3339 instant rounded down to the hour (`hour` granularity only). Interpreted in `timezone`, or in UTC when `timezone` is omitted. A numeric UTC offset is rejected when `timezone` is set; use a calendar day or a `Z` (UTC) instant. Must use the same form as `from`. Defaults to today (day) or the current hour (hour) in that timezone when omitted. Window may not exceed 365 days at `day` or 30 days at `hour` granularity. IANA timezone identifier (for example `Asia/Kathmandu` or `America/New_York`) to report the statistics in. It is the single source of timezone: day and hour boundaries, and the relative window defaults used when `from` and `to` are omitted, are computed in this timezone instead of UTC, so a timezone with a sub-hour offset (such as India at +05:30 or Nepal at +05:45) still gets correct local-day and local-hour totals. When it is set, a `from` or `to` given as a calendar day names a local day in this timezone, and one given as an instant stays an absolute point in time but is rounded down to its hour and bucketed in this timezone (so the hour boundaries are local, not UTC). To avoid specifying the zone twice, a `from` or `to` that carries its own numeric UTC offset (for example `+05:45`) is rejected when `timezone` is set; use a calendar day or a `Z` (UTC) instant instead. Defaults to UTC. Bucket grain of the series: `day` (default) or `hour`. Echoed back as `period.grain`. Possible values: `day`, `hour` The window and bucket grain the response covers, echoed from the request, plus the freshness boundary the data is current to. Inclusive start of the window. A calendar day (YYYY-MM-DD, in the requested `timezone`) on the day grain; on the hour grain, an RFC 3339 UTC instant marking the start of the first hour bucket, which falls on a local hour boundary when `timezone` is set. Inclusive end of the window. A calendar day (YYYY-MM-DD, in the requested `timezone`) on the day grain; on the hour grain, an RFC 3339 UTC instant marking the start of the last hour bucket, which falls on a local hour boundary when `timezone` is set. The bucket grain of the series, either `day` or `hour`. 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 is near-real-time but not live; use this field to label data freshness rather than assuming the numbers are to-the-second. Null when the freshness boundary is not being reported. Single-row aggregate of the mailbox's email activity across the full requested period. Counts are sums of per-bucket counts across the window; latency percentiles are computed across the whole period rather than summed per bucket. Rates are null when their denominator is zero. Distinct email messages the mailbox sent that were accepted, counted at the message level and summed per bucket across the period. Distinct recipients accepted for delivery after suppression filtering. Reported on time buckets and the period summary; omitted on breakdown rows, whose rollups do not carry it. Distinct recipients whose message was processed and handed off for delivery. Distinct recipients whose message the receiving mail server accepted. 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. Distinct recipients with a permanent delivery failure (invalid address or non-existent domain). Distinct recipients with a transient delivery failure (mailbox full or server temporarily unavailable). Distinct recipients bounced by an upstream policy block (relaying denied, blocklisted domain). Distinct recipients bounced because the receiving mail server blocked the sending IP for reputation reasons. Distinct recipients bounced where the receiving server's response did not allow precise classification. Fraction of bounced recipients that hard bounced, computed as `hard / bounced`. Null when `bounced` is zero. Fraction of bounced recipients that soft bounced, computed as `soft / bounced`. Null when `bounced` is zero. Fraction of bounced recipients that admin bounced, computed as `admin / bounced`. Null when `bounced` is zero. Fraction of bounced recipients that block bounced, computed as `block / bounced`. Null when `bounced` is zero. Fraction of bounced recipients with undetermined classification, computed as `undetermined / bounced`. Null when `bounced` is zero. Distinct recipients who reported the message as spam via a feedback loop. Distinct recipients whose delivery the receiving server temporarily delayed and is still being retried. Distinct recipients rejected before any delivery attempt. Includes recipients on the workspace suppression list, transmissions that could not be completed, message-generation failures, and recipients refused by sending policy. The per-recipient `rejection_reason` field on `GET /v1/email/messages/{message_id}/recipients` surfaces the specific cause. Out-of-band bounce events: distinct failure notifications received after the receiving server had initially confirmed delivery. Counted as deduplicated events, not unique recipients. Recipients who remain in-inbox in this scope after all bounce signals resolve, computed as `delivered - oob_bounces`. Use this as the base for engagement-rate denominators. Clamped to 0 when `oob_bounces` exceeds `delivered`. Total recipients in this scope who did not receive the message, computed as `bounced + oob_bounces`. Share of this scope's delivery attempts that resulted in an out-of-band bounce, computed as `oob_bounces / (delivered + bounced)`. Null when there were no attempts. Share of this scope's delivery attempts that resulted in a message remaining in-inbox, computed as `effective_delivered / (delivered + bounced)`. Null when there were no attempts. Share of this scope's delivery attempts that ultimately failed (inband or out-of-band), computed as `all_bounces / (delivered + bounced)`. Because `oob_bounces` counts events rather than recipients, `all_bounces` can exceed the attempt count; the rate is clamped to 1. Null when there were no attempts. Spam complaints in this scope relative to effectively delivered recipients, computed as `complained / effective_delivered`. Complaints are attributed by event time, so a scope can record more of them than it effectively delivered, pushing the rate above 1. Null when `effective_delivered` is zero. 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). 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. Distinct recipients who opened at least once, including opens auto-fetched by inbox privacy features. 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. Distinct click events, counting repeat clicks from the same recipient. Distinct recipients who clicked at least once. Distinct unsubscribe events, recorded via the list-unsubscribe header or the footer link. 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. 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. 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. p50, p95, and p99 latency percentiles in milliseconds for one latency family over the bucket. Percentiles are approximate (computed from a high-volume aggregation pipeline). All three are null together when no qualifying event contributed a latency measurement in the bucket. Median (50th percentile) latency in milliseconds. Null when no qualifying event contributed a measurement. 95th percentile latency in milliseconds. Null when no qualifying event contributed a measurement. 99th percentile latency in milliseconds. Null when no qualifying event contributed a measurement. p50, p95, and p99 latency percentiles in milliseconds for one latency family over the bucket. Percentiles are approximate (computed from a high-volume aggregation pipeline). All three are null together when no qualifying event contributed a latency measurement in the bucket. Median (50th percentile) latency in milliseconds. Null when no qualifying event contributed a measurement. 95th percentile latency in milliseconds. Null when no qualifying event contributed a measurement. 99th percentile latency in milliseconds. Null when no qualifying event contributed a measurement. p50, p95, and p99 latency percentiles in milliseconds for one latency family over the bucket. Percentiles are approximate (computed from a high-volume aggregation pipeline). All three are null together when no qualifying event contributed a latency measurement in the bucket. Median (50th percentile) latency in milliseconds. Null when no qualifying event contributed a measurement. 95th percentile latency in milliseconds. Null when no qualifying event contributed a measurement. 99th percentile latency in milliseconds. Null when no qualifying event contributed a measurement. Distinct emails the mailbox received, summed per bucket across the period. One row per bucket in the period, in chronological order. Buckets with no activity are included with zero counts. The day (YYYY-MM-DD) or instant (RFC 3339, on the bucket boundary) this point covers, matching the period's grain. Distinct email messages the mailbox sent that were accepted in this bucket, counted at the message level (one per accepted send regardless of how many recipients it addresses). Every other sent-mail metric in `delivery` and `engagement` is recipient-level or event-level. Distinct recipients accepted for delivery after suppression filtering. Reported on time buckets and the period summary; omitted on breakdown rows, whose rollups do not carry it. Distinct recipients whose message was processed and handed off for delivery. Distinct recipients whose message the receiving mail server accepted. 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. Distinct recipients with a permanent delivery failure (invalid address or non-existent domain). Distinct recipients with a transient delivery failure (mailbox full or server temporarily unavailable). Distinct recipients bounced by an upstream policy block (relaying denied, blocklisted domain). Distinct recipients bounced because the receiving mail server blocked the sending IP for reputation reasons. Distinct recipients bounced where the receiving server's response did not allow precise classification. Fraction of bounced recipients that hard bounced, computed as `hard / bounced`. Null when `bounced` is zero. Fraction of bounced recipients that soft bounced, computed as `soft / bounced`. Null when `bounced` is zero. Fraction of bounced recipients that admin bounced, computed as `admin / bounced`. Null when `bounced` is zero. Fraction of bounced recipients that block bounced, computed as `block / bounced`. Null when `bounced` is zero. Fraction of bounced recipients with undetermined classification, computed as `undetermined / bounced`. Null when `bounced` is zero. Distinct recipients who reported the message as spam via a feedback loop. Distinct recipients whose delivery the receiving server temporarily delayed and is still being retried. Distinct recipients rejected before any delivery attempt. Includes recipients on the workspace suppression list, transmissions that could not be completed, message-generation failures, and recipients refused by sending policy. The per-recipient `rejection_reason` field on `GET /v1/email/messages/{message_id}/recipients` surfaces the specific cause. Out-of-band bounce events: distinct failure notifications received after the receiving server had initially confirmed delivery. Counted as deduplicated events, not unique recipients. Recipients who remain in-inbox in this scope after all bounce signals resolve, computed as `delivered - oob_bounces`. Use this as the base for engagement-rate denominators. Clamped to 0 when `oob_bounces` exceeds `delivered`. Total recipients in this scope who did not receive the message, computed as `bounced + oob_bounces`. Share of this scope's delivery attempts that resulted in an out-of-band bounce, computed as `oob_bounces / (delivered + bounced)`. Null when there were no attempts. Share of this scope's delivery attempts that resulted in a message remaining in-inbox, computed as `effective_delivered / (delivered + bounced)`. Null when there were no attempts. Share of this scope's delivery attempts that ultimately failed (inband or out-of-band), computed as `all_bounces / (delivered + bounced)`. Because `oob_bounces` counts events rather than recipients, `all_bounces` can exceed the attempt count; the rate is clamped to 1. Null when there were no attempts. Spam complaints in this scope relative to effectively delivered recipients, computed as `complained / effective_delivered`. Complaints are attributed by event time, so a scope can record more of them than it effectively delivered, pushing the rate above 1. Null when `effective_delivered` is zero. 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). 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. Distinct recipients who opened at least once, including opens auto-fetched by inbox privacy features. 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. Distinct click events, counting repeat clicks from the same recipient. Distinct recipients who clicked at least once. Distinct unsubscribe events, recorded via the list-unsubscribe header or the footer link. 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. 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. 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. p50, p95, and p99 latency percentiles in milliseconds for one latency family over the bucket. Percentiles are approximate (computed from a high-volume aggregation pipeline). All three are null together when no qualifying event contributed a latency measurement in the bucket. Median (50th percentile) latency in milliseconds. Null when no qualifying event contributed a measurement. 95th percentile latency in milliseconds. Null when no qualifying event contributed a measurement. 99th percentile latency in milliseconds. Null when no qualifying event contributed a measurement. p50, p95, and p99 latency percentiles in milliseconds for one latency family over the bucket. Percentiles are approximate (computed from a high-volume aggregation pipeline). All three are null together when no qualifying event contributed a latency measurement in the bucket. Median (50th percentile) latency in milliseconds. Null when no qualifying event contributed a measurement. 95th percentile latency in milliseconds. Null when no qualifying event contributed a measurement. 99th percentile latency in milliseconds. Null when no qualifying event contributed a measurement. p50, p95, and p99 latency percentiles in milliseconds for one latency family over the bucket. Percentiles are approximate (computed from a high-volume aggregation pipeline). All three are null together when no qualifying event contributed a latency measurement in the bucket. Median (50th percentile) latency in milliseconds. Null when no qualifying event contributed a measurement. 95th percentile latency in milliseconds. Null when no qualifying event contributed a measurement. 99th percentile latency in milliseconds. Null when no qualifying event contributed a measurement. Distinct emails the mailbox received in this bucket.