Getting started with the Flexmail transactional API

The Flexmail transactional API lets you send triggered, one-to-one emails from your application, order confirmations, password resets, invoices, and anything else that fires in response to a specific user action. This article walks you through the setup process from account to first send. The transactional API only supports one recipient per message. It cannot be used for bulk or marketing sends. See 'Marketing email vs. transactional email' for the full explanation.

Prerequisites

• A Flexmail account. You need one to use the transactional API, even if you're only sending transactional email and not using the marketing features.
• Access to your domain's DNS settings to configure email authentication.
• Developer access to your application to integrate the API.

Step 1: Set up your Flexmail account

If you don't have an account yet, sign up at flexmail.be/en/signup. If you already have an account, activate the transactional trial from the dashboard widget. The trial gives you up to 1,000 sends and 30 days to test.

Your account is also where you manage billing, both your marketing and transactional subscriptions are handled from the same place.

Step 2: Verify your sender address

Before you can send, you need to verify the email address you'll use in the From field.

1. Go to Settings, then Add or remove senders.
2. Add the email address you want to send from.
3. Flexmail sends a verification email to that address, click the link to confirm. This proves you own the mailbox you're sending from.

Step 3: Set up email authentication

Configure SPF, DKIM, DMARC, and a custom return-path for the domain of your sender address. These DNS records prove that your emails genuinely come from you, which is how inbox providers like Gmail decide whether to deliver your email to the inbox or reject it.

Detailed DNS configuration instructions are in the Flexmail Email API documentation , under the Email authentication section.

Step 4: Create a personal access token

The transactional API uses HTTP Basic authentication. Your account ID is the username; a personal access token is the password.

1. Go to Settings, then API, then Personal access tokens.
2. Click Create new token and give it a descriptive name.
3. Copy the token and store it securely. It won't be shown again.

Step 5: Send your first message

The API documentation includes a curl example under Getting started. Edit it with your credentials, recipient details, and subject line, then run it in your terminal. Check the recipient's inbox to verify delivery.

Step 6: Integrate into your application

With a successful test send confirmed, you're ready to integrate the API into your application. The full documentation covers:

• Message sending: all parameters for the send endpoint
• Personalisation: dynamic content in your transactional templates
• Webhooks: real-time event notifications for sends, deliveries, bounces, opens, and clicks

Webhooks are particularly valuable for transactional email: they let your application know immediately

when a message was delivered, bounced, or opened, without polling the API.

API documentation and support

Full API documentation is available at email-api.flexmail.eu/documentation.

If you get stuck at any point, the Flexmail support team is available at support@flexmail.eu. Transactional API questions are handled by the same team that supports the marketing interface.

Next steps

•        See 'Marketing email vs. transactional email' to understand when to use each type.

•        Review the full API documentation at email-api.flexmail.eu/documentation for all endpoint parameters and webhook event types.