Merge pull request #3722 from replicatedhq/return-path-dkim

add return path config docs

bypassing code owner review as Paige is out for 2w

Author: AmberAlston

docs/vendor/enterprise-portal-configure.mdx

@@ -67,6 +67,8 @@ This section describes options for customizing the emails sent to customers thro
 
 ### Configure Email Sender
 
+Adding a sender address helps ensure that your emails are delivered and are not marked as spam.
+
 To configure customer emails:
 
 1. In the Vendor Portal, go to **Enterprise Portal > Customer Emails**.
@@ -75,7 +77,9 @@ To configure customer emails:
 
    [View a larger version of this image](/images/enterprise-portal-customer-emails.png)
 
-1. For **Email Sender Verification**, in **From email address**, add the email address that you want to use as the sender for all system notifications sent to your customers, then click **Continue**. Adding a sender address helps ensure that your emails are delivered and are not marked as spam.
+1. For **Email Sender Verification**, in **From email address**, add the email address that you want to use as the sender for all system notifications sent to your customers, then click **Continue**.
+
+1. Follow the steps in the wizard to verify the domain by adding the DKIM and Return-Path to your domain registrar.
 
     After the domain is verified automatically, the email address is displayed under **Verified Sender Address**.