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Schedule the next Mailjet newsletter from the last one

Your weekly newsletter keeps its layout and only the subject changes. Every week someone duplicates the last campaign, edits the details and schedules it.

Cotlet does it in your own Mailjet account with list_campaigns, duplicate_campaign, update_campaign, set_campaign_recipients and schedule_campaign, called by your AI agent, an n8n workflow or a script.

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Hosted · nothing to install or maintain

Can Mailjet do this on its own?

Mailjet's guides describe scheduling one send at a time, up to 60 days ahead, from the Review & Send page (checked 22 Oct 2026). The REST API has endpoints to create a draft, set its schedule and send it. The official MCP server is read-only and cannot schedule anything.

How you do it in Mailjet today

  1. Open Campaigns and the Sent tab, click the cogwheel icon next to last week's campaign and choose Duplicate. Mailjet opens the Campaign Details page of the copy.
  2. Change the campaign name, which only you see, check the language and pick the contact list.
  3. Click Design email, then set the Subject line and the From field in the Email Editor. The subject limit is 100 characters.
  4. Send a test email to up to 10 recipients to check the result.
  5. Click Review & Send and choose to send now or schedule it for a future date, up to 60 days ahead.
  6. A scheduled campaign cannot be edited. To change it you cancel it, edit the content and schedule it again.

How to schedule the next Mailjet newsletter from the last one

Prompt

Duplicate last week's "Weekly digest" campaign in Mailjet, set the subject to "This week at Northside, Oct 23", send it to the Newsletter list and schedule it for Friday 8:00 London time.
  1. 01

    Find last week's campaign

    list_campaigns with status "sent" and the name you gave returns the newest match. If a draft with this week's name already exists, the agent stops and asks, so you never get two drafts.

  2. 02

    Copy it

    duplicate_campaign makes a draft from the sent campaign with the name you pass. The design is copied as it is. The agent does not edit it, because the layout stays in the Email Editor.

  3. 03

    Change the subject and sender

    update_campaign sets the name, subject and sender of the draft. The sender address must be one Mailjet lets you use: your login address or an address or domain you validated.

  4. 04

    Check who gets it

    set_campaign_recipients picks the list and, if you ask, a segment. On the Free plan the agent warns when the list is larger than the 200 addresses an Email Editor campaign can reach.

  5. 05

    Schedule it with your OK

    schedule_campaign takes the send time with its offset and returns the time Mailjet stored. It reaches your contacts, so it waits for your OK by default. Mailjet does not let you edit a scheduled campaign, so the agent re-reads the draft first.

What you get back

Example data

Copied "Weekly digest, Oct 15" as the draft "Weekly digest, Oct 23"
Subject: "This week at Northside, Oct 23"
List: Newsletter
Scheduled for Fri Oct 23, 08:00 (UTC+01:00) after your OK

Other ways to ask

  • Every Thursday, copy the newest "Weekly digest" and schedule it for Friday 8:00, with the date in the subject.
  • Copy the October newsletter into a draft for November and schedule nothing.
  • Schedule the draft "Black Friday teaser" for November 20 at 9:00 and tell me when it is queued.

What Mailjet allows, and what to know first

  • Mailjet schedules a campaign up to 60 days ahead.
  • Mailjet does not let you edit a scheduled campaign: you cancel it, edit it and schedule it again.
  • Mailjet allows a subject of up to 100 characters and advises under 70 for better open rates.
  • Mailjet lets you use only sender addresses you own or manage, and your login address is the default sender.
  • On the Free plan a campaign made in the Email Editor goes to at most 200 addresses, and more than 1,000 stored contacts puts a sending hold on the account.

schedule_campaign asks for your OK by default. To run it weekly without you, switch confirmation off for that tool in your dashboard.

Sources: Mailjet Help: Creating and sending your first campaign · Mailjet Help: How to copy or duplicate a campaign · Mailjet Help: Understanding Mailjet Free Plan Limits

Call schedule_campaign from a script

curl

curl -X POST https://cotlet.dev/api/v1/mailjet/campaigns/7203318846/schedule \
  -H "Authorization: Bearer $COTLET_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"send_at":"2026-10-23T08:00:00+01:00"}'

Example response

{
  "campaign_id": 7203318846,
  "name": "Weekly digest, Oct 23",
  "subject": "This week at Northside, Oct 23",
  "status": "scheduled",
  "scheduled_for": "2026-10-23T08:00:00+01:00"
}

MCP: add https://cotlet.dev/mcp/v1 with the same key; the call is mailjet_write → schedule_campaign. Example data.

Schedule it in n8n, Make, Zapier or cron

Mailjet tools this automation uses

Cotlet Mailjet tools used to schedule the next Mailjet newsletter from the last one
Tool Parameters
list_campaigns status, search, cursor
duplicate_campaign campaign_id, name
update_campaign campaign_id, name, subject, sender_name, sender_email
set_campaign_recipients campaign_id, list_id, segment
schedule_campaign campaign_id, send_at
All 14 Mailjet tools with descriptions

Frequently asked questions

Is it safe to connect Mailjet to Cotlet?

Yes. You sign in to Mailjet yourself, in your own Cloud Browser in the EU, and we never save your password. Your agents only get Mailjet once you enable it, every background request is listed, and the browser profile is stored encrypted with AES-256-GCM, the cipher 1Password uses for its vaults. The AI model never sees a login, posts and messages wait for your OK, and Disable for agents cuts access in one click. Independent scanners grade cotlet.dev A+ on Qualys SSL Labs, securityheaders.com and Mozilla Observatory; live results are on https://cotlet.dev/security.

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