MailerSend warmup and automated inbox placement setup

Use a generated MailerSend SMTP user to connect a verified domain. Complete the provider’s account review and recipient restrictions before using external placement seeds or starting warmup.

Prepare the sender in MailerSend

1. Add and authenticate the sending domain in MailerSend using the DNS records it supplies.
2. Complete Get approved with accurate company and sending-use details. Confirm your account permits delivery to the recipients required by your test; a sandbox can have a restricted audience.
3. Open Email > Domains, manage the domain, and select Generate new user in the SMTP section.
4. Name the SMTP user and copy or download its generated username and password. The password is displayed once.

Use an account approved for your intended sending, and include production traffic when checking provider limits. See MailerSend getting started and account review and SMTP credential scope for provider setup details.

Connect and verify in MailSlurp

Open Email warmup > Create warmup or Inbox placement > Automations > Create automation. Select MailerSend in the sender step, or reuse the existing verified connection for that sender.

Enter a recognizable connection name, sender name and authorized From address, followed by these values:

Field	Value
Connection type	SMTP
Host	smtp.mailersend.net
Port and security	587, STARTTLS
Username	Generated SMTP username
Password	Generated SMTP password

Choose Verify and continue and complete the delivery test before proceeding. Check credential verification and the received test separately: an authenticated connection does not by itself prove message delivery. Reuse this connection for both features instead of creating another copy of the same sender.

Schedule automated inbox placement

1. Open Inbox placement automations and select Create automation.
2. Select the verified MailerSend connection.
3. Set the schedule name, Frequency and Inbox audience. Account allowance and provider limits must cover every seed recipient in each run.
4. Enter the subject and text body, retaining {{trackingToken}} in at least one of them. MailSlurp substitutes a fresh marker for each test.
5. Select Create automation, then inspect the saved schedule and next run.
6. Use Run now for an immediate check if needed. Inspect a later scheduled execution separately to confirm the recurrence is working.

Open the linked report and wait for all targets to settle. Compare inbox, provider tabs, spam and not-received results with the same messages in MailerSend’s activity. A provider delivery event does not prove inbox placement. Pausing the schedule stops future scheduled tests while preserving its history.

The scheduled subject and text body are the message being tested. To check a finished campaign with different HTML, links or routing, use the manual placement workflow through the original sending path.

Start and monitor warmup

Open Email warmup > Create warmup and choose the same connection. Set the sender goal, ramp preset or custom daily volumes, time zone and sending window. Select managed content or an allowed custom subject and plain-text body. Review the resolved coverage and estimated usage before starting.

Controlled coverage measures paced delivery to managed inboxes. Core coverage adds provider placement checkpoints when your plan and the available coverage permit them. Review accepted sends, observed controlled receipts and completed checkpoint folders separately; a progress percentage alone does not establish successful delivery.

Choose maintenance when you want ongoing activity after the ramp. For a finite program, disable maintenance and follow the remaining ramp and any final checkpoint through its terminal state. Pause while investigating a persistent send failure, then resume the existing program after correcting it. A short successful run does not establish a lasting reputation improvement.

Review capacity, usage and errors

Warmup and placement automation share a Delivery Sender allocation. Creating or verifying a connection does not consume an enabled sender seat; starting a workflow can enable it. Pausing retains the allocation. After stopping warmup and pausing all automations that use it, disable the sender in Settings > Sending connections if you want to release that capacity.

Read the account’s included allowance and credit weights before sending. Warmup uses weighted message credits; standalone and automated placement use placement-test allowance. Warmup placement checkpoints use warmup credits rather than consuming another standalone placement test. Provider recipient limits still apply to every message.

Successful SMTP authentication does not complete account review or lift recipient restrictions. If approval is pending or rejected, address the reason supplied by MailerSend before attempting the workflow. SMTP users can send for any verified domain on the account; they are not domain-scoped credentials. Check the From domain and account permission before retrying a failed delivery.

See warmup configuration and results for pacing and program controls, and placement automation and reports for API workflows and exports.