Update Managed DMARC docs

content/docs/managed-dmarc.md

@@ -10,16 +10,27 @@ implemented by more and more email providers, is easy with Keila!
 
 <managed-note></managed-note>
 
-## 1. Pick an unused subdomain.
+## 1. Create a *Send with Keila* Sender
+Create a [Sender](/docs/senders) in your Keila project and select the *Send with Keila* option.
+Make sure you can receive emails at the *From address*
+(e.g. `[email protected]`) so you can receive the confirmation email.
+
+## 2. Pick your Mail From Domain
 Choose a subdomain that is not currently used for anything else. This
-subdomain will become your *FROM domain*. Common choices are something
-like `mailings.example.com` or `send.example.com`.
+subdomain will become your *Mail From Domain*. Common choices include `mailings.example.com` or `send.example.com`.
+
+**Note:** You can’t use the *Mail From Domain* in your *From address*. This
+means if you configure *send.example.com* as your *Mail From Domain*, you should
+still use an email address on your principal domain (e.g.
+*[email protected]*) as your *From address* and not an email address on
+your *Mail From Domain* (i.e. **don’t use** *[email protected]*).
+
 
-## 2. Update your DNS
+## 3. Update your DNS
 
 Add the following entries to your DNS settings:
 
-**Connect your chosen subdomain with CNAME**:  
+**Connect your Mail From Domain with CNAME**:  
 `CNAME` `*your-subdomain*.example.com` `public.keila.io`
 
 **Add the Keila DKIM key**:  
@@ -28,7 +39,7 @@ Add the following entries to your DNS settings:
 **Enable DMARC for your main domain**:  
 `TXT` `example.com` `v=DMARC1; p=none`
 
-## 3. Almost done!
+## 4. Submit the Domain Connection Form
 
 Now you’re almost done! Just submit our domain configuration form and we’ll take
 care of the rest and get in touch with you.