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Send Customer.io mail through your SMTP server

By default, Customer.io takes care of your email delivery. However, you can tell Customer.io to send mail through any other SMTP server.

Upsides to doing this

  • You’re in full control.
  • We won’t charge you anything based on the volume of email you send. You’ll only pay the plan cost based on the number of profiles in your account.
  • We’ll still handle your open and click tracking.
  • We’ll keep a full copy of your sent emails associated with the recipient.

Downsides to doing this

  • Customer.io won’t have a feedback loop for data from the sending ESP.
  • Data about delivered, bounced and spammed emails won’t be visible in Customer.io. We have integrations providing delivered, spam and bounce data with Mandrill, Mailgun, and Sendgrid

Configure custom SMTP settings

  1. Head to Custom SMTP Settings in the Email & Actions section of your Account Settings.
  2. Click the Add Custom SMTP Settings button, and fill out the form:

Adding custom SMTP settings

When you save these settings, we’ll start sending emails through your own SMTP account.

Notes:

  • Your port cannot be 25, 465, or 587; most major providers also allow delivery using port 2525 (like in our screenshot above). If you need alternatives, the best thing to do is consult your delivery provider’s documentation for ports that work with their service.

  • If you enabled custom SMTP, you are no longer required to complete the authentication process. The SPF and DKIM records need to be set up for your chosen STMP. Inside Customer.io, you only need to validate the domain ownership and the CNAME record if you want the tracking links to be branded using your domain rather than customeriomail.com.

If you have any questions about setting this up, get in touch!