My environment:
192.168.10.1 AD domain control
There are two domain users, y1 and y2
Their email addresses are x1@xxx.com and x2@xxx.com

192.168.10.2 Debian11:Postfix+dovecot+ad domain authentication integration

When I deploy the postfix+dovecot+ad integrated authentication, when the email prefix of the domain user is inconsistent with the domain user name, the following error appears in the log file:
Dec 29 19:32:24 a2 postfix/smtpd[18295]: connect from unknown[192.168.10.4]
Dec 29 19:32:39 a2 postfix/smtpd[18295]: NOQUEUE: reject: RCPT from unknown[192.168.10.4]: 550 5.1.1 x2@a.b: Recipient address rejected: User unknown in virtual mailbox table; from=x1@a.b to=x2@a.b proto=ESMTP helo=<[192.168.10.4]>
Dec 29 19:32:39 a2 postfix/smtpd[18295]: lost connection after RCPT from unknown[192.168.10.4]
Dec 29 19:32:39 a2 postfix/smtpd[18295]: disconnect from unknown[192.168.10.4] ehlo=2 starttls=1 mail=1 rcpt=0/1 rset=1 commands=5/6

When the email address of the domain user is consistent with the user name, everything can be sent and received normally

I want the mailbox service to work normally when the domain user's email address and user name are inconsistent. What can I do to achieve this?

I just contacted postfix，Can someone help me?

Thank you very much.

An email user by default must be a valid email address in the domain or on the host. Define x1 & x2 as valid users within the domain served.

This restriction is part of the general requirement that mail servers must not allow unidentified users to send mail thus helping to reduce the significant problem with spam email.

It may be possible to do that within the /etc/aliases file and then running 'newaliases' as shown within the file itself.