Last week I introduced a safety net based on a compatibility level. If you upgrade to a Postfix version that has a higher compatibility level than the main.cf compatibility level (default: 0) then Postfix will use backwards-compatible default settings and log warnings when the old Postfix configuration uses a default setting that is going to change. You can then decide to make the old default setting permanent before updating the main.cf compatibility level.
Compatibility level 1 changes defaults to: append_dot_mydomain=no, smtputf8_enable=yes and chroot=n. Details of warning messages are in http://www.postfix.org/postconf.5.html#compatibility_level What else needs to be considered? There are more settings whose defaults can be confusing to people who aren't familiar with 10+ years of Postfix history. - relay_domains (default: $mydestination). This should be empty. - mynetworks-style (default: subnet). This should be "host". - parent_domains_matches_subdomains. I am reluctant to change this because it affects so many Postfix features. A cascade of warning messages could be confusing. I want to finish this before the next stable release. I'd rather avoid a trickle of breaks with every stable release, as that would detract from Postfix's reputation. Wietse
