@@ -87,7 +87,7 @@ If the recipient's domain name supports DNSSEC and has published a [DANE TLSA](h
Domain policy records allow recipient MTAs to detect when the _domain_ part of of the sender address in incoming mail has been spoofed. All outbound mail is signed with [DKIM](https://en.wikipedia.org/wiki/DomainKeys_Identified_Mail) and "quarantine" [DMARC](https://en.wikipedia.org/wiki/DMARC) records are automatically set in DNS. Receiving MTAs that implement DMARC will automatically quarantine mail that is "From:" a domain hosted by the box but which was not sent by the box. (Strong [SPF](https://en.wikipedia.org/wiki/Sender_Policy_Framework) records are also automatically set in DNS.) ([source](management/dns_update.py))
# User Policy
### User Policy
While domain policy records prevent other servers from sending mail with a "From:" header that matches a domain hosted on the box (see above), those policy records do not guarnatee that the user portion of the sender email address matches the actual sender. In enterprise environments where the box may host the mail of untrusted users, it is important to guard against users impersonating other users. The box restricts the envelope sender address that users may put into outbound mail to either a) their own email address (their SMTP login username) or b) any alias that they are listed as a direct recipient of. Note that the envelope sender address is not the same as the "From:" header.
