This Postfix build behaves differently from the upstream postfix-3.5.8. It's because in RHEL-8 backward compatibility is kept to postfix-3.3.1. For the upstream postfix-3.5.8 behavior either run the following commands: # postconf info_log_address_format=external # postconf smtpd_discard_ehlo_keywords= # postconf rhel_ipv6_normalize=yes Or go through the following steps: 1. Change the configuration option 'info_log_address_format' to 'external'. In RHEL-8 it's by default set to 'internal' to mitigate [Incompat 20191109]. 2. Change the configuration option 'smtpd_discard_ehlo_keywords' to ''. In RHEL-8 it's by default set to 'chunking' to mitigate [Incompat 20180826]. 3. Add RHEL-8 specific configuration option 'rhel_ipv6_normalize' and set it to 'yes'. In RHEL-8 this option was added to mitigate [Incompat 20190427]. Details from the upstream RELEASE_NOTES: [Incompat 20191109] Postfix daemon processes now log the from= and to= addresses in external (quoted) form in non-debug logging (info, warning, etc.). This means that when an address localpart contains spaces or other special characters, the localpart will be quoted, for example: from=<"name with spaces"@example.com> Older Postfix versions would log the internal (unquoted) form: from=<name with email@example.com> The external and internal forms are identical for the vast majority of email addresses that contain no spaces or other special characters in the localpart. Specify "info_log_address_format = internal" for backwards compatibility. The logging in external form is consistent with the address form that Postfix 3.2 and later prefer for table lookups. It is therefore the more useful form for non-debug logging. [Incompat 20180826] The Postfix SMTP server announces CHUNKING (BDAT command) by default. In the unlikely case that this breaks some important remote SMTP client, disable the feature as follows: /etc/postfix/main.cf: # The logging alternative: smtpd_discard_ehlo_keywords = chunking # The non-logging alternative: smtpd_discard_ehlo_keywords = chunking, silent_discard See BDAT_README for more. [Incompat 20190427] Postfix now normalizes IP addresses received with XCLIENT, XFORWARD, or with the HaProxy protocol, for consistency with direct connections to Postfix. This may change the appearance of logging, and the way that check_client_access will match subnets of an IPv6 address.