Comment 2 for bug 644538

Error is:
newaliases: fatal: /etc/mailname/: cannot open file: No such file or directory

You replaced /etc/aliases by the package maintainer version, overriding local changes. You might want to edit that file again to reflect your configuration.

That said, if, like mentioned in bug 644534, there was a security breach, I'd advise to completely reinstall the system.