Using Trusty I was able to install version 2.11.0-1ubuntu1.2 from proposed and complete the verification steps in the test case. I can confirm that postfix started as expected with the new version, but failed to start with the current version in the archive.
Using Trusty I was able to install version 2.11.0-1ubuntu1.2 from proposed and complete the verification steps in the test case. I can confirm that postfix started as expected with the new version, but failed to start with the current version in the archive.
My log from Trusty attached