Reinstall would be the quickest and easiest, depending on which distribution you're running. For Debian/Ubuntu,
Code:
apt-get --reinstall install postfix
I'm 85% sure this will not overwrite any existing configuration, but of course, you probably want to back everything up anyway (files don't normally delete themselves). Or, if you have a system with the exact same architecture, distribution, and release, you can simply copy that specific file to the disadvantaged system.
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Code:
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