Expand on reasons custom domains are good

Build your own email reputation.

microsoft-365/admin/setup/domains-faq.yml

@@ -71,7 +71,7 @@ sections:
         answer: |
           A domain is a unique name that appears after the **@** sign in email addresses, and after **www.** in web addresses. It typically takes the form of your organization's name and a standard Internet suffix, such as *yourbusiness.com* or *stateuniversity.edu.* 
             
-          Using a custom domain like "**rob\@contoso.com**" with Microsoft 365 can help build credibility and recognition for your brand. 
+          Using a custom domain like "**rob\@contoso.com**" with Microsoft 365 can help build credibility and recognition for your brand. It may also have a positive effect on your email reputation, depending on the provider, making it less likely that your email will be mis-identified as "spam".
             
           You can [buy a domain in Microsoft 365 and we will set it up automatically](../get-help-with-domains/buy-a-domain-name.md), or you can buy or bring one you already own from a domain registrar.