SRU justification: the postfix package in natty runs in a chroot by default, but does not know to copy nss modules from the multiarch library paths to set up the chroot. As a result, various sorts of NSS resolution, such as mapping port names to numbers or resolving the hostnames of incoming connections, will fail. This will break postfix in various common configurations.
1. install postfix and configure it to use a smart host, specifying only a hostname (no port) for the smart host.
2. verify that there is no /var/spool/postfix/lib/<triplet> directory.
3. send mail and verify that the mail delivery fails because postfix can't resolve 'smtp' to a port number.
4. upgrade postfix to the SRU version
5. verify that after upgrade, there is a /var/spool/postfix/lib/<triplet> directory
6. send mail and verify that it now can be sent to the smarthost successfully.
Risk of regression: if I've done something wrong and the tar command fails under certain conditions, postfix will fail to start.
Binary package hint: postfix
I haven't yet determined the cause of this, but after upgrading to natty from maverick, postfix smtpd DNS lookups always fail when running in chroot (which is the default). This can be seen by lines like "postfix/smtpd: connect from unknown" in mail.log, where unknown should be the hostname. After editing master.cf so that smtpd is not in a chroot, hostname lookups work normally, as can be seen in mail.log.
There were no changes in my configuration other than upgrading from maverick to natty. Hostname lookups worked fine in chroot with maverick.
DistroRelease: Ubuntu 11.04
Package: postfix 2.8.2-1ubuntu1
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic 220.127.116.11
Uname: Linux 2.6.38-8-generic i686
Date: Sun Apr 17 16:46:24 2011
UpgradeStatus: Upgraded to natty on 2011-04-16 (1 days ago)