Schedule your emails in advance with scheduled emails

Until now, Lettermint sent every email the moment we received it. Anything that had to go out later was your problem to solve. A cron job that picks up pending emails, a delayed queue, or a calendar reminder so the campaign goes out on time.

Now you can schedule an email by passing a date and time along with it. We hold on to the email and send it when that moment arrives. If plans change, you can reschedule or cancel it right up until it goes out.

Scheduled emails

With broadcast emails you can line up a newsletter or campaign well ahead of time. Your weekly update lands every Tuesday at 10:00, even if you finished it on Monday. And a Black Friday campaign no longer means sitting at your laptop at midnight.

For transactional email you schedule the moment you have the information. Someone signs up, so you queue the follow-up for three days later in the same request. Someone books an appointment, so the reminder for the day before is already set. If they cancel, you pull the reminder.

You pass the time when you send the email. That can be ISO 8601 (opens in a new window), in UTC or with an offset, or plain English like "tomorrow at 9am", "in 2 hours" or "Friday at 3pm ET". You can schedule anywhere from 30 seconds to 30 days ahead.

How it works

Scheduling works through the API and SMTP, and our SDKs support it out of the box. In a batch, each email can have its own send time, which comes in handy when one list covers recipients across several timezones. Here's what it looks like through the API.

      curl -X POST "https://api.lettermint.co/v1/send" \
  -H "x-lettermint-token: lm_project_token" \
  -H "Content-Type: application/json" \
  -d '{
    "from": "hello@acme.com",
    "to": ["recipient@example.com"],
    "subject": "Appointment reminder",
    "html": "<p>Your appointment starts tomorrow at 10:00.</p>",
    "scheduled_at": "2026-09-17T09:00:00+02:00"
  }'

    

Over SMTP, add the X-LM-Scheduled-At header to your email. We strip it before the email reaches the recipient.

      X-LM-Scheduled-At: 2026-09-17T09:00:00+02:00

    

Reschedule or cancel a scheduled email

A scheduled email shows up in your dashboard with the status Scheduled and the date and time it will be sent. You can reschedule or cancel it from there, or through the API using the message ID. You get that ID back when you send the email, and you can also find it in your dashboard or through the Team API.

Available on Growth and Pro

Scheduled emails is included in the Growth and Pro plans. The full details, including supported time formats and the batch endpoint, are in the documentation.