Nylas

Nylas Messages API

Messages. List, search, read, update and delete email messages. Send immediately, schedule a send and cancel a scheduled send, with folders, signatures and attachments alongside.

GitHub OpenAPI

Operations 9

Each operation below carries the questions people ask an LLM about it and the instructions they give an agent to run it. Generated by API Evangelist overlay

GET /v3/grants/{grant_id}/messages List or search a user's email messages · Return all Messages #
Ask an LLM
“How do I list the emails in a connected user's mailbox?”
“Can I filter a user's messages to only unread ones that have attachments?”
Tell an agent
List the latest {limit} messages in mailbox {grant_id}.
Find messages in {grant_id} from {from} with the subject {subject}.
GET /v3/grants/{grant_id}/messages/{message_id} Retrieve a single email message · Return a Message #
Ask an LLM
“How can I fetch the full contents of one email by its message ID?”
“Can I get just the headers or selected fields of a single message?”
Tell an agent
Open message {message_id} in mailbox {grant_id}.
Fetch message {message_id} for grant {grant_id} including its {fields}.
PUT /v3/grants/{grant_id}/messages/{message_id} Mark, star or move an email message · Update message attributes #
Ask an LLM
“How do I mark an email as read or unread through the API?”
“Can I star a message or move it to another folder?”
Tell an agent
Mark message {message_id} in {grant_id} as unread.
Star message {message_id} for grant {grant_id}.
DELETE /v3/grants/{grant_id}/messages/{message_id} Delete an email message · Delete a message #
Ask an LLM
“Does deleting an email send it to Trash or remove it permanently?”
“How do I permanently delete an email instead of trashing it?”
Tell an agent destructive · confirm first
Delete message {message_id} from mailbox {grant_id}.
Hard delete email {message_id} for grant {grant_id} so it skips the Trash.
PUT /v3/grants/{grant_id}/messages/clean Clean up email bodies into plain content · Clean messages #
Ask an LLM
“Can I strip signatures, links and images out of email bodies to get clean text?”
“Is there a way to convert an email's HTML into Markdown?”
Tell an agent
Clean messages {message_id} in mailbox {grant_id} and return them as Markdown.
Clean email {message_id} for {grant_id}, removing links and images.
POST /v3/grants/{grant_id}/messages/send Send or schedule an email from a user's mailbox · Send a Message #
Ask an LLM
“How do I send an email on behalf of a connected user?”
“Can I schedule an email to go out at a later time?”
Tell an agent
Send an email from {grant_id} to {to} with subject {subject}.
Schedule a message from mailbox {grant_id} to {to} to be sent at {send_at}.
GET /v3/grants/{grant_id}/messages/schedules List a user's scheduled emails · Return scheduled messages #
Ask an LLM
“Which emails does this user have scheduled to send later?”
“Can I see scheduled messages that have already gone out as well as pending ones?”
Tell an agent
List all scheduled messages for mailbox {grant_id}.
Show me every send schedule on grant {grant_id}.
GET /v3/grants/{grant_id}/messages/schedules/{scheduleId} Check the status of one scheduled email · Return a scheduled message #
Ask an LLM
“How can I check whether a specific scheduled email has been sent yet?”
“Can I look up a single scheduled message by its schedule ID?”
Tell an agent
Get scheduled message {scheduleId} for mailbox {grant_id}.
Check the send status of schedule {scheduleId} on grant {grant_id}.
DELETE /v3/grants/{grant_id}/messages/schedules/{scheduleId} Cancel a scheduled email before it sends · Cancel a scheduled message #
Ask an LLM
“How do I stop a scheduled email from going out?”
“How close to the send time can I still cancel a scheduled message?”
Tell an agent destructive · confirm first
Cancel scheduled message {scheduleId} in mailbox {grant_id}.
Unschedule send {scheduleId} for grant {grant_id} so it never goes out.

Specifications

⚙
OpenAPI
https://raw.githubusercontent.com/api-evangelist/nylas/refs/heads/main/openapi/nylas-messages-api-openapi.yml

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OpenAPI Specification

nylas-messages-api-openapi.yml Raw ↑ 
openapi: 3.2.0
info:
  title: Nylas Messages API
  version: v3
  summary: The complete Nylas v3 API — Email, Calendar, Contacts, Notetaker, Scheduling, Administration, and Migration.
  description: The Nylas API is designed using the REST ideology to provide simple and predictable URIs to access and modify objects.
  contact:
    url: https://www.nylas.com/
  x-provenance:
    method: harvested
    first_party: true
    publisher: Nylas
    source: https://developer.nylas.com/_spec-files/nylas-api.yaml
    harvested: '2026-08-21'
    sha256: 7ff001d571e163b1ffe22178741b59f813d8208ec878157a839a33dc2c13fd35
    bytes: 1666223
    note: 'Published by Nylas as the unified contract for the Nylas v3 API and stored verbatim; API Evangelist added only this provenance block. Submitted by the provider in api-evangelist/nylas#1 and verified against the live URL before harvest: OpenAPI 3.1.0, 118 paths, 208 operations, 174 component schemas, 100% of operations carrying summary, description, tag and a unique operationId, x-code-samples on 208 of 208. This document REPLACES a 22-operation scaffold API Evangelist derived from reading the documentation, now quarantined under openapi/_scaffold/.'
  x-evidence:
  - url: https://developer.nylas.com/_spec-files/nylas-api.yaml
    what: the published unified contract, harvested verbatim 2026-08-21 (200, text/yaml, 1,666,223 bytes)
  - url: https://developer.nylas.com/.well-known/api-catalog
    what: RFC 9727 linkset advertising that URL as service-desc for api.us.nylas.com and api.eu.nylas.com (200, application/linkset+json)
servers:
- url: https://api.us.nylas.com
  description: U.S.
- url: https://api.eu.nylas.com
  description: E.U.
security:
- ACCESS_TOKEN: []
- NYLAS_API_KEY: []
tags:


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# Full source: https://raw.githubusercontent.com/api-evangelist/nylas/refs/heads/main/openapi/nylas-messages-api-openapi.yml