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AutoSend x Customer.io
Customer.io is a messaging platform for marketing, transactional emails, push notifications, and in-app messages. By default, Customer.io uses its built-in email service, but you can configure it to use AutoSend SMTP for better deliverability and email tracking.

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Prerequisites

Verified Domain

Make sure you have a verified domain added in AutoSend to send emails from.

API Key

Create a new API key for SMTP authentication or use the existing one.

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Configuration

2

Add Custom SMTP Server

  1. Click on Custom SMTP
  2. Select Add Custom SMTP Server
Supabase Step 2
3

Select SMTP Provider

Select Other SMTP as your provider type and click Continue to set up.
Supabase Step 3
4

Enter SMTP Credentials

Fill in the following settings:
FieldValue
Addresssmtp.autosend.com
Port587 (or 465 for implicit TLS)
AuthenticationSelect Plain
Usernameautosend
PasswordYour AutoSend API key (AS_xxx)
Supabase Step 1
Customer.io does not support port 25. Use port 587, 465, or 2525 instead.
Click Finish set up to save your configuration.
5

Add a Sending Domain

Before sending emails, add a sending domain in Customer.io that matches your verified domain in AutoSend.
  1. Go to Settings → Workspace Settings → Email
  2. Under Sending Domains, add your domain (e.g., yourdomain.com)
Supabase Step 5
6

Send a Test Email

Create a test campaign or broadcast to verify your SMTP configuration is working correctly.You can also check the Email Activity dashboard to verify the email was sent through AutoSend.

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Troubleshooting

  • Verify your SMTP credentials are correct - Check that your sender email domain is verified in AutoSend - Ensure you’ve added a sending domain in Customer.io - Check Customer.io’s delivery logs for SMTP connection errors
  • Double-check your API key is correct - Ensure you’re using autosend as the username - Verify your API key is active in the AutoSend dashboard
  • Verify the server address is smtp.autosend.com - Try using port 465 or 2525 if port 587 fails - Remember that port 25 is not supported by Customer.io
  • Ensure your domain has proper DNS records (SPF, DKIM, DMARC) - Use a professional sender name and address - Check your domain reputation in AutoSend

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Next Steps

https://mintcdn.com/autosend-13920f5c/nx_wYfWx3qeZwg1C/icons/domain.svg?fit=max&auto=format&n=nx_wYfWx3qeZwg1C&q=85&s=9393f9f9b0f7029e6ba8acf2bc09d864

Verify Your Domain

Set up SPF, DKIM, and DMARC for better deliverability
https://mintcdn.com/autosend-13920f5c/nx_wYfWx3qeZwg1C/icons/email-activity.svg?fit=max&auto=format&n=nx_wYfWx3qeZwg1C&q=85&s=2ecad7369f217ee7d03c3d8dfdd36d22

Email Activity

Monitor your email delivery and engagement
https://mintcdn.com/autosend-13920f5c/nx_wYfWx3qeZwg1C/icons/webhook.svg?fit=max&auto=format&n=nx_wYfWx3qeZwg1C&q=85&s=14ad6675c71731ac04f786559a813ee1

Webhooks

Set up webhooks to track email events in real-time
https://mintcdn.com/autosend-13920f5c/nx_wYfWx3qeZwg1C/icons/smtp.svg?fit=max&auto=format&n=nx_wYfWx3qeZwg1C&q=85&s=d1993edda392d54c3f704a9a4bb04442

SMTP Introduction

Learn more about AutoSend SMTP configuration