aaP_esales2000
In the Linux system, the root user can send emails by default. However, in order to enhance system security, you can restrict the root user from sending mail by configuring the mail server or changing the settings of the mail client.

Here are some ways you can restrict the root user from sending mail:

Configure mail server: You can configure mail server to prevent root user from sending mail. Specifically, you can create a mail filtering rule on the mail server to prevent the root user from sending mail. For example, in a Postfix mail server, you would add the following to the /etc/postfix/main.cf file:

smtpd_sender_restrictions = check_sender_access hash:/etc/postfix/sender_access

Then, add the following to the /etc/postfix/sender_access file:

root REJECT

This will change mailx's default sender address, preventing root from sending mail.

Change the email address of the root user: You can change the email address of the root user to prevent the root user from sending emails. For example, on an Ubuntu system, you can edit the /etc/aliases file and change root's email address to a non-real email address:

root: /dev/null

This will prevent the root user from sending mail.
Note that changing the configuration of the root user may affect the normal operation of the system. Therefore, make sure you know what you are doing and back up important data before changing your system configuration.

      When i use
      smtpd_sender_restrictions = check_sender_access hash:/etc/postfix/sender_access

      Im receiving an error while trying to send emails from the primary email account that Im using on my WordPress (info@mydomain.com).
      when I remove the sender restrict option from the config file. then it's working again and I can send emails from info@mydomain.com.
      i didn't check yet if this issue is with all email accounts.

      Mailer: Other SMTP
      SMTP Error: The following recipients failed: someemailaddress@gmail.com: : Sender address rejected: Server configuration error

        Is it possible to send after cancellation?
        It is recommended to check whether the sender email configuration of wordpress is misconfigured?
        Also check whether the ssl of the mail server is configured correctly?
        "mail.135mailtest.com" is replaced with your domain name
        You can use this command to check whether the correct SSL is configured
        openssl s_client -connect mail.135mailtest.com:587 -starttls smtp
        or
        openssl s_client -connect mail.135mailtest.com:465 -starttls smtp

        If the display is not OK, please re-apply for SSL

        aaP_esales2000

            aaPanel_Kern
            Verify return code: 0 (ok)

            The sender email is config correctly and the SSL is also ( using Chain SSL ).

            Can I give you temporary access to the aaPanel?

                aaPanel_Kern
                Can you give me a hint on what to look? because it's happening only when I try to reject sending emails from the root.

                That is the error that I'm receiving

                Versions:
                WordPress: 6.0.3
                WordPress MS: No
                PHP: 7.4.33
                WP Mail SMTP: 3.8.0

                Params:
                Mailer: smtp
                Constants: Yes
                ErrorInfo: SMTP Error: The following recipients failed: recipient@me.com: : Sender address rejected: Server configuration error
                Host: mail.mydomain.com
                Port: 465
                SMTPSecure: ssl
                SMTPAutoTLS: bool(true)
                SMTPAuth: bool(true)

                Server:
                OpenSSL: OpenSSL 1.0.2u 20 Dec 2019

                Debug:
                Email Source: WP Mail SMTP Pro
                Mailer: Other SMTP
                PHPMailer was able to connect to SMTP server but failed while trying to send an email.
                Email Source: WP Mail SMTP Pro
                Mailer: Other SMTP
                SMTP Error: The following recipients failed: recipient@me.com: : Sender address rejected: Server configuration error

                SMTP Debug:
                2023-05-08 05:33:55 Connection: opening to ssl://mail.mydomain.com:465, timeout=300, options=array()

                2023-05-08 05:33:55 Connection: opened

                2023-05-08 05:33:55 SERVER -> CLIENT: 220 mail.mydomain.com ESMTP Postfix (3.4.7)

                2023-05-08 05:33:55 CLIENT -> SERVER: EHLO tikair.co.il

                2023-05-08 05:33:55 SERVER -> CLIENT: 250-mail.mydomain.com250-PIPELINING250-SIZE 102400000250-VRFY250-ETRN250-AUTH PLAIN LOGIN250-ENHANCEDSTATUSCODES250-8BITMIME250-DSN250-SMTPUTF8250 CHUNKING

                2023-05-08 05:33:55 CLIENT -> SERVER: AUTH LOGIN

                2023-05-08 05:33:55 SERVER -> CLIENT: 334 VXNlcm5hbWU6

                2023-05-08 05:33:55 CLIENT -> SERVER: [credentials hidden]

                2023-05-08 05:33:55 SERVER -> CLIENT: 334 UGFzc3dvcmQ6

                2023-05-08 05:33:55 CLIENT -> SERVER: [credentials hidden]

                2023-05-08 05:33:55 SERVER -> CLIENT: 235 2.7.0 Authentication successful

                2023-05-08 05:33:55 CLIENT -> SERVER: MAIL FROM:noreply@mydomain.com

                2023-05-08 05:33:55 SERVER -> CLIENT: 250 2.1.0 Ok

                2023-05-08 05:33:55 CLIENT -> SERVER: RCPT TO:recipient@me.com

                2023-05-08 05:33:55 SERVER -> CLIENT: 451 4.3.5 noreply@mydomain.com: Sender address rejected: Server configuration error

                2023-05-08 05:33:55 SMTP ERROR: RCPT TO command failed: 451 4.3.5 noreply@mydomain.com: Sender address rejected: Server configuration error

                2023-05-08 05:33:55 CLIENT -> SERVER: QUIT

                2023-05-08 05:33:55 SERVER -> CLIENT: 221 2.0.0 Bye

                2023-05-08 05:33:55 Connection: closed

                SMTP Error: The following recipients failed: recipient@me.com: noreply@mydomain.com: Sender address rejected: Server configuration error

                  That my mail config

                  readme_directory = /usr/share/doc/postfix3-3.4.7/README_FILES
                  meta_directory = /etc/postfix
                  shlib_directory = /usr/lib/postfix
                  virtual_mailbox_domains = sqlite:/etc/postfix/sqlite_virtual_domains_maps.cf
                  virtual_alias_maps = sqlite:/etc/postfix/sqlite_virtual_alias_maps.cf, sqlite:/etc/postfix/sqlite_virtual_alias_domain_maps.cf, sqlite:/etc/postfix/sqlite_virtual_alias_domain_catchall_maps.cf
                  virtual_mailbox_maps = sqlite:/etc/postfix/sqlite_virtual_mailbox_maps.cf, sqlite:/etc/postfix/sqlite_virtual_alias_domain_mailbox_maps.cf
                  smtpd_sasl_type = dovecot
                  smtpd_sasl_path = private/auth
                  smtpd_sasl_auth_enable = yes
                  smtpd_recipient_restrictions = permit_sasl_authenticated, permit_mynetworks, reject_unauth_destination
                  smtpd_use_tls = yes
                  smtp_tls_security_level = may
                  smtpd_tls_security_level = may
                  virtual_transport = lmtp:unix:private/dovecot-lmtp
                  message_size_limit = 102400000
                  smtpd_milters = inet:127.0.0.1:11332
                  non_smtpd_milters = inet:127.0.0.1:11332
                  milter_protocol = 6
                  milter_default_action = accept
                  default_process_limit = 100
                  smtpd_client_connection_count_limit = 10
                  smtpd_client_connection_rate_limit = 30
                  queue_minfree = 20971520
                  header_size_limit = 51200
                  smtpd_recipient_limit = 400
                  #smtpd_sender_restrictions = check_sender_access hash:/etc/postfix/sender_access

                  smtpd_tls_chain_files = /www/server/panel/plugin/mail_sys/cert/mydomain.com/privkey.pem,/www/server/panel/plugin/mail_sys/cert/mydomain.com/fullchain.pem
                  tls_server_sni_maps = hash:/etc/postfix/vmail_ssl.map

                  milter_mail_macros = i {mail_addr} {client_addr} {client_name} {auth_authen}

                    aaP_esales2000
                    Hello, is it normal for Send mail to use the relevant user to send mail in the mail server?
                    Is it normal to add a # comment to the configuration of milter_mail_macros and restart postfix?

                        Hello, can you give us your aapanel information? The server first makes a snapshot backup, if possible, please send it to kern@aapanel.com.
                        It is recommended to fill in the following content
                        Post link:
                        SSH IP address, account password and port:
                        aapanel login link address and account password:
                        Website background login information:
                        Email account information:

                        If there is no post link, it will not be possible to know which user's information it is, and the problem will not be processed

                        aaP_esales2000

                            aaPanel_Kern
                            Its because
                            smtpd_sender_restrictions = check_sender_access hash:/etc/postfix/sender_access
                            is comment.
                            If you will uncomment smtp_sender_restrictions.. you will receive an error

                                aaPanel_Kern In the Linux system, the root user can send emails by default. However, in order to enhance system security, you can restrict the root user from sending mail by configuring the mail server or changing the settings of the mail client.

                                Here are some ways you can restrict the root user from sending mail:

                                Configure mail server: You can configure mail server to prevent root user from sending mail. Specifically, you can create a mail filtering rule on the mail server to prevent the root user from sending mail. For example, in a Postfix mail server, you would add the following to the /etc/postfix/main.cf file:

                                smtpd_sender_restrictions = check_sender_access hash:/etc/postfix/sender_access

                                Then, add the following to the /etc/postfix/sender_access file:

                                root REJECT

                                This will change mailx's default sender address, preventing root from sending mail.

                                Change the email address of the root user: You can change the email address of the root user to prevent the root user from sending emails. For example, on an Ubuntu system, you can edit the /etc/aliases file and change root's email address to a non-real email address:

                                root: /dev/null

                                This will prevent the root user from sending mail.
                                Note that changing the configuration of the root user may affect the normal operation of the system. Therefore, make sure you know what you are doing and back up important data before changing your system configuration.

                                aaPanel_Kern Is it possible to send after cancellation?

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