We recently changed our email service from Sparkpost to PoOstmark. If you're using Sparkpost custom domain setup, then there are a few things you need to do on your end to continue to use this feature.  

Disconnect current domain settings on the Settings page, Integrations > Domain Setup. 

In the dropdown, select Postmark, to proceed with setting up the new configuration

Add the domain and click on the "Submit" button 

Copy DKIM Settings

Once submitted, the system will generate DKIM settings. Copy them and add them to DNS settings on the domain provider's side.

After adding DKIM records, click on the "Verify" button at the bottom of the setup. 

After successful integration, you'll see the domain listed in the settings, and you can use your own domain for autoresponder emails. 

In case you have any issues setting up a custom domain, please let us know.