How to Send Emails from Shopify Flow Using SendGrid

Go to signup.sendgrid.com and create an account with your email address.

SendGrid’s free trial runs for 60 days and lets you send up to 100 emails a day, which is plenty to get FlowRelay connected and tested. After the trial, plans start with Essentials at around $19.95 a month, with Pro and Premier tiers above that for higher volume. Check the pricing page for current numbers before you commit to real volume.

SendGrid won’t deliver mail until it knows who you are. In the SendGrid dashboard, open Settings → Sender Authentication.

For a quick start, click Verify a Single Sender and fill in the from name, from email address, reply-to, and your company’s address. SendGrid emails a confirmation link to that address; click it to finish.

For production sending, Domain Authentication is the better option: it verifies your whole domain rather than one address. Add the domain you want to send from, and SendGrid hands you a set of CNAME records (covering SPF and DKIM) plus a TXT record for your DMARC policy to add through your DNS host. Most major DNS providers append your domain automatically, so enter only the hostname portion of each record. Once they’re in place, click Verify; SendGrid allows up to 48 hours for the records to propagate.

Open Settings → API Keys in the SendGrid dashboard and click Create API Key.

Give it a name and choose Full Access. When you connect the key, FlowRelay checks its scopes, and if that lookup is blocked, it falls back to your account profile; a key restricted to Mail Send only is likely to fail both checks. Click Create & View and copy the key right away (it starts with SG. and is 69 characters long), since SendGrid only shows it once.

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 SendGrid.

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

Pick SendGrid from the provider list and paste in the API key you generated (it should start with SG.). FlowRelay verifies the key before saving it. If you want emails to go out under a different name or address than your account default, open Override sender and fill those in, and turn on open or click tracking if you want SendGrid to report on those events.

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.

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 SendGrid 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 through SendGrid and see its delivery status.