Corrective releases of the Postfix mail server -
3.5.1, 3.4.11, 3.3.9 and 3.2.14, in which for correction DANE/DNSSEC when using system library , which broke backwards compatibility in the field of passing DNSSEC flags. In particular, the transmission of the AD DNSSEC flag (authenticated data) was no longer performed by default, but only when a new RES_TRUSTAD flag was specified in "_res.options" in /etc/resolv.conf. Without changing the settings, the AD flag set by the DNS server is no longer passed to applications that call functions like res_search().
In addition, in new releases, the with assembly using the GCC 10 compiler, which is expected to be released in May. Due to backward compatibility changes in GCC, a 'multiple definition' error started to appear when attempting to build Postfix.
Source: opennet.ru