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Revision as of 08:35, 30 April 2021 by Pj (Talk | contribs)


Package Information - postfix3

General Information when upgrading from the stock postfix package

Postfix3 replaces the EL stock postfix packages and will always contain the latest version of postfix available. These packages are backwards compatible with the EL stock postfix packages with the following caveats:

  • Postfix 3.0 introduced the compatibility_level setting which permits backwards compatibility while allowing defaults to change in future versions of postfix as needed. When you upgrade from older versions postfix will maintain many backwards compatible defaults until you update the compatibility_level setting to tell Postfix that you want the newer defaults. Postfix will, however, issue warnings about compatibility_level not being set and also tell you which settings you should change before updating the compatibility_level setting.
  • Postfix 3.0 introduced dynamic map support. With this we have moved support for many table types to individual packages. You will need to install the individual packages for each table type you want support for. To support the same table types as in the EL7 stock postfix packages you should install the following packages: postfix3 postfix3-ldap postfix3-mysql postfix3-pcre
  • Postfix 3.6.0 now requires openssl 1.1.1 or higher. As a result the postfix3 package now requires openssl11-libs from the EPEL repository. Since EPEL is already required to be enabled for use of GhettoForge this should not be an issue, and the required dependency should be pulled in automatically on update.

Instructions for replacing the EL stock postfix packages with the postfix3 packages in GhettoForge

  • Install the gf-release package as per Usage.
  • Use the yum shell command to update your system to postfix3:
	# yum shell --enablerepo=gf-plus
	> remove postfix*
	> install postfix3 postfix3-ldap postfix3-mysql postfix3-pcre

(note that the stock postfix from EL has compiled-in support for ldap, mysql and pcre table types, but you may not need to support all these table types. If you don't feel free to leave them out of the install command above)

	> run

... You will be prompted to update to postfix3 and associated sub-packages.

	> quit
  • Restart Postfix:
	# service postfix restart

...At this point you should have a look in /var/log/maillog. You will see warnings about compatibility_level and various settings that you should change before changing compatibility_level, but other than that Postfix should start up and run and be fully backwards compatible with the stock version you were running before. You can now explicitly set the various settings that Postfix complains about to remove the warnings for them. Do not update the compatibility_level setting until all other settings are fixed and Postfix no longer complains about any of them except for compatibility_level itself.

Note that Postfix 3.6.0 introduced the "respectful_logging" setting. This is also affected by compatibility_level but is not shown if it is unset with compatibility_level set lower than 3.6. When setting compatibility_level to a setting >= 3.6 if you want the old behavior you should explicitly set respectful_logging to "no".

Note that there is a new setting, "known_tcp_ports" in Postfix 3.6.0. The default changes the Postfix behavior to ignore certain service to port mappings from the /etc/services file. Normally this would not be an issue, but if you have custom ports set for any of these services in /etc/services then you should edit this setting accordingly, or explicitly set it empty to revert Postfix to the old behavior of checking /etc/services.

If you have problems or need further assistance feel free to join #ghettoforge or #postfix on the FreeNode IRC network for assistance.

Yum updates

Because the postfix3 packages are in the gf-plus repository you will need to explicitly enable them to get future updates with the "yum update" command. See Usage for details.

Switching back to the stock postfix

Switching back to the stock postfix consists largely of doing the reverse steps from the above. There is one caveat in that the stock postfix packages have a bug where they will attempt to create the alternatives links before the postfix3 package removes them. The easiest way to fix this is to reinstall the stock postfix a second time after it has been installed and it should create the links then:

	# yum shell
	> remove postfix3*
	> install postfix postfix-ldap postfix-mysql postfix-pcre
	> run
	> quit
	# yum reinstall postfix

EL7 only: You should backup your main.cf file and then remove the compatibility_level setting to avoid warnings in the logs from an unrecognised setting:

	# cp /etc/postfix/main.cf /etc/postfix/main.cf.postfix3
	# postconf -X compatibility_level

Then restart postfix and you should be done.