[email protected]
Explanation:
According to the configuration, the postmaster address is set to [email protected]. This means that any system-generated messages or notifications sent to the administrator of this domain will use this address as the sender. The postmaster address is also used to receive messages from external senders who need to contact the administrator for any reason, such as reporting spam or abuse. The postmaster address is a mandatory requirement for any mail server, as specified by the RFC 5321 standard. References:
LPIC-2 exam 202 objectives, topic 207.3, Manage the postfix mail system RFC 5321, section 4.5.1, Postmaster Role