Loops SMTP: Check the Template Payload Before Handoff

If an application can connect to Loops SMTP but the expected email does not appear, check what the application submits before redesigning the message. Loops documents a template-based SMTP route: the body identifies a transactional email and supplies its data. It is not a general instruction to submit an arbitrary HTML design unchanged.

Use Migma to prepare and review the customer-facing message, then have the sending owner verify that the implementation can express Loops’ required payload. Keep the accepted creative and transport evidence together so a connection problem does not turn into an unnecessary rewrite.

This guide is published by Migma. It describes a review workflow, not a native Migma-to-Loops SMTP connector. Loops’ official SMTP instructions were checked on October 20, 2026.

Separate the message from the submission format

A design reference answers what the recipient should read. The submission format answers how the sending provider is told to produce that message. Those are related but different parts of the system.

Loops’ SMTP documentation says to create a transactional email in Loops, then submit a stringified, API-like body containing the transactional identifier, recipient, and data variables. Loops uses the specified template and supplied data to compile the email.

The practical consequence is straightforward: a component that only emits raw HTML needs a compatibility review. Knowing the SMTP host and credentials does not establish that the component can generate the required body. Do not describe a successful connection as a completed creative handoff.

Keep an approved Migma reference

Before troubleshooting, retain the intended copy, hierarchy, links, brand, and variable meanings in Migma. Review brand settings and references so the accepted message is identifiable and consistent.

For a fictional account-confirmation email, the reference might contain a short explanation, one confirmation action, and a support route. The sending owner supplies the actual confirmation URL at send time. The design should not contain a real user’s private link as a reusable example.

Mark which content is fixed and which values are supplied by the application. Record what the primary action must do, not just what the button looks like. If the Loops implementation recreates the design in a provider-hosted template, compare that implementation with the approved Migma reference.

Migma’s export guidance explains its supported handoff options. This article does not establish that a downloaded HTML file can be pasted directly into a Loops SMTP request or that Migma automatically converts it into a Loops template.

Ask the sending owner four compatibility questions

Use the actual integration’s current documentation and a controlled example to answer the following:

1. Which Loops transactional template should this message use?
2. Can the application produce the structured body the Loops SMTP documentation requires?
3. Which data variables does the selected template expect, and where do approved values come from?
4. What evidence will show provider acceptance and the later message outcome?

These questions are more useful than switching ports repeatedly. If the integration’s output format cannot express the payload, the owner needs to select a supported implementation route. Do not weaken validation or improvise a format because the connection itself works.

Loops’ protocol resource discusses host, port, and encryption-mode compatibility as a separate concern. Follow the provider’s current settings as a complete set. Do not combine a port from one tutorial with a TLS mode from another.

Trace the failure at the right boundary

A timeout before connection is different from a rejected payload. A provider-accepted message that later bounces is different again. Ask the owner to identify the last confirmed step and its receipt before assigning the problem to the creative.

This is an original troubleshooting map. It does not promise a particular error code or prescribe undocumented recovery behavior. Use the actual provider and application evidence for the implementation decision.

Verify the selected template and populated data

When the request format is correct, compare the Loops template with the accepted Migma reference. Check the opening, action label, fixed support destination, and any dynamic fields. A valid identifier can still point to the wrong message.

Review an approved populated example. Confirm that the action URL belongs to the intended environment and that the surrounding sentence accurately describes it. A confirmation link, password-reset link, and marketing destination are not interchangeable merely because each is a URL.

If a value is absent, have the implementation owner verify the documented behavior. Do not publish a universal fallback recipe without checking the template and application. Keep credentials and private action links out of shared troubleshooting notes.

Accept the final received message

Run Email Preflight on the Migma reference for the checks it documents. Then review a controlled message from the actual sending route using your team’s approved test process. Preflight does not verify that the application selected the correct Loops transactional template.

Keep the Migma version, Loops template reference, variable mapping, submission receipt, and final-message review together. If the payload and delivery path are correct but the creative differs, make a focused correction in the responsible template and repeat the relevant check.

Start with one email type. Once its customer-facing content and provider submission agree, apply the same acceptance method to the next message. That is a stronger result than a green connection indicator beside an unverified email.

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