Schedule Emails and Optimize Deliverability with the Outbox Endpoint Beta

Optimize emails for 99% or better deliverability with Outbox Endpoint from Nylas.

Schedule Emails and Optimize Deliverability with the Outbox Endpoint Beta

Ready, Set, Send

Empower your users to schedule and send emails that land in the inbox, not in SPAM.

Each year, Nylas enables billions of emails to get delivered. Our email API is backed by powerful email analytics, user-friendly email threading, inbox management and search, automatic provider detection, and many other power-features. Today, we are pleased to announce a new Beta addition to our Email API – a new Outbox endpoint, which allows you to build scheduled email send capabilities that land in the inbox with-near perfect deliverability.

Eliminate Most Email Send Error Messages

Error handling is something that all developers should consider when building any type of software and sending emails is no different. Third-party email providers all have their own limitations for API requests, email sending, user bandwidth quotas, and more; it’s only a matter of time before your development team encounters HTTP errors 403, 429, 500, 503, 504, and the like. 

Nylas detects when an account experiences these problems and automatically takes the appropriate steps to work around them whenever possible. With Nylas, you no longer need to worry about your users hitting account and API limitations, we take care of that for you. 

Read our technical guide on email API send errors to learn more

Improve Email Deliverability Instantly – Nylas Assists With All Industries

Whether your users are in sales, recruiting, real estate, legal, or any other industry, email delivery is paramount. Nylas already enables best-in-class deliverability and open rates (approximately 99% for deliverability and above 21% for open rates in CRM’s). Now, with our outbox endpoint, you can help users increase email responses and engagement rates by sending emails that land in the inbox at the optimal time. Here are a few examples of how outbox can benefit users in two email-centric industries:

  • CRM (Customer Relationship Management Software):  With the Outbox endpoint, sales reps using your CRM can write emails and schedule them for optimal times to increase open rates. Sales reps send a large number of emails each day, particularly if they’re doing heavy outbounding, which may cause them to hit the daily provider rate limits. Gmail, for example, limits business users to 500 emails per day. With the Nylas API’s smart logic, any email sent over the daily maximum is rescheduled and sent as soon as the 24 hour period has passed. Now, emails don’t bounce back to the sales rep; they get sent to their prospects as soon as possible.


  • ATS (Applicant Tracking Systems):  The Outbox endpoint enables recruiters to reach large numbers of candidates without worrying about daily rate limits or poor deliverability. Most recruiters are managing multiple job reqs and a large candidate pool, and need to contact candidates when they are most likely to respond. Using the outbox endpoint, recruiters can schedule their emails to send later at the optimal times for open rates, helping them build pipeline faster and close candidates sooner.

Build Email Send Functionality In a Fraction of the Time

The Outbox endpoint is a dramatic step forward for the Nylas Email API’s send capabilities, and it behaves in a very similar manner to the Send endpoint. One key difference is that you can include a send_at attribute that indicates a future time to send the email later; this is represented as a Unix epoch timestamp.

curl -X POST '' \
-H 'Authorization: Bearer ACCESS_TOKEN' \
-d '{
 "send_at": 1008720000,
  "subject": "One Email API to rule them all",
  "body": "Keep it secret, keep it safe... or share it with your friends.",
  "to": [{
          "email": "",
          "name": "My Friend"

Nylas will queue this email to be sent at the earliest possible opportunity and you can check the status of this queue at any moment by sending a GET request to the Outbox endpoint.

curl -X GET '' -H 'Authorization: Bearer ACCESS_TOKEN'

This will return a list of all pending email send tasks with an indication of when they will be sent (this example is abbreviated for readability).

    "send_at": 1008720000,
    "status": "pending",
    "subject": "One Email API to rule them all",
    "body": "Keep it secret, keep it safe... or share it with your friends.",
    "id": "aorj598vm4"
    "to": [{
        "email": "",
        "name": "My Friend"

You can modify the time that the email will be sent by making a PUT request to the Outbox endpoint for the specific message id.

curl -X PUT '{id}' \
-H 'Authorization: Bearer ACCESS_TOKEN'
-d '{ "send_at": 1608155100 }'

Head over to the docs to find more details about the technical details of the Outbox endpoint.

Learn how the outbox endpoint empowers your users to do more with their time. Speak to a platform specialist now.

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