How to Send Emails from Shopify Flow Using SMTP

Where these live depends on where your mail comes from. A web host or shared hosting panel usually lists them under Email Accounts or Mail Settings. Google Workspace and Microsoft 365 both publish SMTP relay details in their admin docs. Dedicated transactional providers, including several that FlowRelay also supports directly, such as Postmark, SendGrid, Mailgun, and Resend, offer SMTP as an alternative to their API in their dashboards, often under a heading like SMTP, SMTP Relay, or Integrations.

Whichever source you’re using, you’re looking for four things: a host (something like smtp.yourprovider.com), a port, a username (often a full email address, but sometimes an account ID or API-key-style string), and a password. That password is frequently a generated app password, SMTP token, or API key rather than your normal account password, so use whatever your provider specifically labels for SMTP access.

The port determines how the connection gets encrypted, and providers don’t always make the choice obvious. Port 587 is the most common default: it starts the connection in plain text and upgrades to an encrypted one with STARTTLS. Port 465 connects with TLS from the first handshake and is treated that way by FlowRelay, so use it if your provider lists it. Port 25 is the traditional SMTP port, but most cloud platforms block outbound traffic on it, so providers rarely recommend it for application sending.

If your provider lists more than one option and you’re not sure which to pick, 587 is the safest default.

Install FlowRelay from the Shopify App Store and accept the requested permissions.

On first launch, FlowRelay shows a short setup checklist: set your sender name and email, connect a provider, and send a test email. The next step covers connecting over SMTP.

In FlowRelay, open Settings, find Email delivery, and click Manage providers to open the Connect email provider dialog.

Pick SMTP from the provider list and fill in the host, port, username, and password you found in the first step. FlowRelay tests the connection before saving it, so a typo in the host or the wrong port shows up immediately rather than after your first real send. If you want emails to go out under a different name or address than the account tied to these credentials, open Override sender and fill those in.

Click Connect. Whichever provider you connect first becomes your Primary, and FlowRelay routes all outbound mail through it. You can connect a second provider later as an automatic Fallback, which is worth doing if your SMTP source has a sending limit you might hit.

Open Shopify Flow, create a new workflow, and pick a trigger (Order created is a common one to start with). Add the Send transactional email action; it shows up in the action list once FlowRelay is installed.

You’ll need to fill in a few fields on the action: an email address for the recipient (this can pull straight from the trigger, like the customer’s email), a subject line, and the body, which is the actual HTML content of the email. There’s also an optional preview text field for the snippet shown in inbox previews. For the body, you can write plain HTML or use Liquid to pull in order details, customer names, and other data from the workflow.

Save the workflow and turn it on.

Before you trust a live trigger, use the Send test email button in FlowRelay’s settings. It confirms your SMTP connection is wired up correctly and shows you where the message lands.

Once that test email arrives, run your Flow workflow under real conditions, like placing a test order, and check FlowRelay’s delivery log to confirm the email went out and see its delivery status.