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Get engagement by email client

GET
/v1/email/stats/clients
const { data } = await bird.email.stats.byClient({
  from: "2026-05-01",
  to: "2026-05-31",
  limit: 25,
});
for (const row of data) console.log(row.email_client, row.engagement.unique_opens);
Response200
{
  "period": {
    "from": "2026-05-01",
    "to": "2026-05-25",
    "data_as_of": "2026-05-25T14:03:10Z"
  },
  "data": [
    {
      "email_client": "Apple Mail",
      "os": "iOS",
      "device_type": "mobile",
      "engagement": {
        "opens": 5420,
        "opens_non_prefetched": 3210,
        "unique_opens": 3640,
        "unique_opens_non_prefetched": 2480,
        "clicks": 924,
        "unique_clicks": 621
      }
    }
  ],
  "total": 9,
  "next_cursor": "eyJ2IjoxLCJzIjoiXCIyMDI2LTA1LTI1VDE0OjAzOjEwWlwiIiwiaSI6IjAxOTJmM2IxLTRjN2UtN2EyYi05ZDYxLThmM2E1YzJlN2I0MCJ9",
  "prev_cursor": null,
  "refresh_cursor": "eyJ2IjoxLCJzIjoiXCIyMDI2LTA1LTI1VDE2OjQyOjAxWlwiIiwiaSI6IjAxOTJmM2IxLTllMDQtN2NkMy1iODE3LTJhNmY0ZDFjOGUwOSJ9"
}

Returns engagement counts (opens and clicks) for the requested period, grouped by the email client, operating system, or device type they were recorded from. Use it for the classic view of opens by mail client, for example the share of opens from Apple Mail compared with Gmail and Outlook. The reading environment is only known from open and click events, so rows have engagement counts but no delivery counts or rates.

Use group_by to choose the facet: email_client (the default), os, or device_type. Each row fills in the facet you chose and leaves the other two null. Rows are ranked by the sort metric, unique_opens by default, and paginated with the requested limit (50 by default, 200 at most).

Rows 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.

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). Defaults to 30 days before to when omitted.

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.

group_bystring

Which reading-environment facet to group rows by. email_client (default) groups by mail client; os groups by operating system; device_type groups by device type. Each row populates the chosen facet and leaves the other two null.

Possible values: email_client, os, device_type

sortstring

Metric to rank rows by, applied descending. It defaults to unique_opens. Only engagement counts are sortable. This breakdown has no rates.

Possible values: opens, opens_non_prefetched, unique_opens, unique_opens_non_prefetched, clicks, unique_clicks

limitinteger

Maximum number of client rows to return, ranked by the sort field descending.

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

Client breakdown rows, ranked by the sort metric (default unique_opens) descending. Empty when no opens or clicks with a detected client occurred in the period.

Show child attributes
data.email_client
nullable string
required

The mail client this row aggregates (for example Gmail, Apple Mail, Outlook). Populated only when group_by=email_client. Null otherwise.

data.os
nullable string
required

The operating system this row aggregates (for example iOS, Android, Windows, macOS). Populated only when group_by=os. Null otherwise.

data.device_type
nullable string
required

The device type this row aggregates (for example mobile, desktop, tablet). Populated only when group_by=device_type. Null otherwise.

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, 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.

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.

total
integer
required

Total number of distinct values of the requested group_by facet 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.

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