reword IP address allow list guidance

Author: thestinger

README.md

@@ -54,8 +54,8 @@ For example, making an initial configuration:
     sqlite3 attestation.db "INSERT INTO Configuration VALUES ('emailUsername', '[email protected]'), ('emailPassword', '<password>'), ('emailHost', 'mail.grapheneos.org'), ('emailPort', '465')"
 
 The `attestation.service` unit only allows the service to communicate over `localhost` by default
-so either the `IPAddressDeny`/`IPAddressAllow` configuration needs to be removed or extended to
-include your DNS server and mail server IP addresses.
+so the `IPAddressDeny`/`IPAddressAllow` configuration either needs to be removed or extended to
+include your DNS server and mail server IP addresses when using a remote mail server.
 
 ### Handling abuse