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GET
https://api.us.nylas.com/v3/metrics/send

Return send metrics by domain or sender

Returns send counts and rates grouped by sending domain, sender address, or recipient domain. Use it to find which of your domains or Agent Accounts has the highest bounce rate, or which mailbox provider is rejecting your mail. Rows are sorted by sent volume by default.

NYLAS API KEY

Parameters

Query parameters

group_bystring

What to group by. agent_account groups by the sender email address. recipient_domain covers the last 90 days at most.

sending_domainagent_accountrecipient_domain
Default: "sending_domain"
sortstring

The sort order, as <key>:<asc|desc>. The key is one of key, sent, delivery_rate, bounce_rate, or complaint_rate.

Default: "sent:desc"
Example: "bounce_rate:desc"
limitinteger

The maximum number of rows to return. When there are more groups, the rest are combined into one final row with the key (others).

Default: 25
startstring<date>

The first day of the window, as a UTC date in YYYY-MM-DD format. Defaults to six days before end, so the default window covers 7 days. A window can cover up to 365 days.

Example: "2026-10-01"
endstring<date>

The last day of the window, as a UTC date in YYYY-MM-DD format. Defaults to today. Today is included as a partial day.

Example: "2026-10-30"
sending_domainstring

Return only data for messages sent from this domain.

Example: "mail.example.com"

Responses

request_idstring

The request ID.

dataobject
GEThttps://api.us.nylas.com/v3/metrics/send?group_by=sending_domain&sort=sent%3Adesc&limit=25&start=2026-10-01&end=2026-10-30&sending_domain=mail.example.com

Find your API key in the Nylas Dashboard under API Keys in your application settings.