Creating a Custom Bounce Domain

April 29, 2017 Contributors

By creating a custom bounce domain, you can customize the address that is used for the Return-Path header (which denotes the destination for out-of-band bounces). This bounce domain overrides the default Return-Path (also known as the envelope FROM) value of "" for all messages sent.

Please note that your root domain should not be configured as a custom bounce domain. As a result, there are two options for adding and verifying custom bounce domains in SparkPost:

Option 1:

  1. Add your root domain (e.g. as a sending domain. Only add the TXT record provided in SparkPost to your DNS and ignore the CNAME verification.

  2. Add a separate subdomain (e.g. to be used as a bounce domain. Only add the CNAME record for that subdomain to your DNS and ignore the TXT verification.

Option 2:

  1. Add a subdomain (e.g. to be used as both a sending domain and a bounce domain. Add both the TXT record and CNAME record provided in SparkPost to your DNS.

To configure a bounce domain, choose the subdomain you would like to use (e.g. and add the following CNAME record to your DNS settings:

Hostname Type Value CNAME

This DNS record will ensure that out-of-band/asynchronous bounces are routed to SparkPost for processing.

Once you have configured your DNS settings, register and verify the domain with SparkPost by following the steps below.

Using The SparkPost UI

If you prefer to use the SparkPost UI, you can create multiple bounce domains or single bounce domain that will be used for all of your outgoing mail.

  1. Select Account and then Sending Domains.
  2. Click the New Domain button to add a sending domain. Again, please add a subdomain to avoid any issues with your root domain.
  3. Navigate to your DNS and add the displayed CNAME record from SparkPost.
  4. Select the "Verify CNAME Record" orange text in the Setup For Bounce record box.
  5. Make sure the domain is verified by the green check mark. Please note that there is up to a 5 minute delay for compliance verification before the domain can be used.

Once the CNAME record is verified in SparkPost, you will notice an orange button in the CNAME record box that says "Use this domain as your default bounce domain?" Turn this on if you want all of your transmissions to use this bounce domain. If you plan to configure multiple bounce domains, please refer to the end of the article for more information on how to set the bounce domain in your transmission.

Using The SparkPost API

If you prefer to set up a sending domain as a bounce domain via the API, use the following instructions:

  1. Register the domain with SparkPost by using the sending domains create endpoint

  2. CNAME-verify the domain by using the sending domains verify endpoint. Here’s an example API call to CNAME-verify the domain:

  3. Optionally set the domain as your account default bounce domain so that it is automatically used as the bounce domain for all messages sent through the account. Here’s an example API call to set as the account default bounce domain:

Using Multiple Custom Bounce Domains

If you configure multiple bounce domains, you will need to specify the desired bounce domain directly in your transmission request:

  1. SMTP – You will need to specify the bounce domain in the SMTP MAIL FROM command.

  2. REST API – You will need to add the bounce domain to the domain part of the return_path field. Note that the SparkPost servers will overwrite the local part of the return_path address, so this local part can be anything in your transmission request.

    For example: