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WebPanel => Postfix => Topic started by: daowen on June 01, 2025, 09:39:15 AM

Title: Error found - Mail Server Manager
Post by: daowen on June 01, 2025, 09:39:15 AM

Found the following issue when attempting to reduce spam:

rDNS Check (recommended): Drop all emails if no rDNS/PTR

When this option is checked, there should be a positive return running the following command:

Code: [Select]

postconf | grep reject_unknown_client_hostname
We should see this returned:

Code: [Select]

smtpd_client_restrictions = reject_unknown_client_hostname
Upon inspection, after selecting the option and rebuilding the mail server, it failed to change the one line in the main.cf file:

Code: [Select]

smtpd_client_restrictions = reject_unknown_client
Manually edited the file and injected the  "_hostname" to resolve.

Title: Re: Error found - Mail Server Manager
Post by: overseer on June 01, 2025, 11:45:07 AM

To further reduce spam, consider this stanza in main.cf:

Code: [Select]

smtpd_sender_restrictions =
        permit_mynetworks,
        permit_sasl_authenticated,
        check_sender_access pcre:/etc/postfix/reject_domains hash:/etc/postfix/sender_access,
        reject_unknown_sender_domain,
        reject_unknown_reverse_client_hostname,
        reject_unknown_client_hostname