some copyedits on admin / email

config/locales/client.en.yml

@@ -86,7 +86,7 @@ en:
 
       name:
         title: "Name"
-        instructions: "The longer version of your name; does not need to be unique."
+        instructions: "The longer version of your name; does not need to be unique. Used for alternate @name matching and shown only on your user page."
         too_short: "Your name is too short."
         ok: "Your name looks good."
       username:

config/locales/server.en.yml

@@ -470,6 +470,8 @@ en:
 
       - Have you checked to make sure the IPs of the server the mail originates from are [not on any email blacklists][4]?
 
+      - Have you verified that your email server is *definitely* sending a fully qualified hostname in its HELO message? This will cause your email to be rejected by many mail services.
+
       We hope you received this email deliverability test OK!
 
       Good luck,