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I trying to get an email server up and running on a raspberry pi running Raspbian Buster.

In my postfix checks I am getting a strange notification about a symlink that I definitely did not create myself. The warning is postfix/postfix-script: warning: symlink leaves directory: /etc/postfix/./makedefs.out I have done two clean installs thinking it might be malicious, and every time it comes back, so I am assuming it is somehow part of the configuration or has something specifically to do wiht the postfix version on raspberry pi.

In any event, the following message appears when running my postfix check:

sudo postfix check
postfix: Postfix is running with backwards-compatible default settings
postfix: See http://www.postfix.org/COMPATIBILITY_README.html for details
postfix: To disable backwards compatibility use "postconf compatibility_level=2" and "postfix reload"
postfix/postfix-script: warning: symlink leaves directory: /etc/postfix/./makedefs.out
  1. Does anyone have any idea what exactly this symlink is doing and who/what is creating it?
  2. Is it something to worry about and
  3. How do I get rid of this error message in my postfix check?
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    Came here from google since I see the same warning. However, I doubt that this needs "fixing" at all. For me it is a link /etc/postfix/makedefs.out -> /usr/share/postfix/makedefs.out. As a comment in this file states this file documents how Postfix was built for your machine and contains what looks indeed like a config how to build postfix. Not sure for what it is needed, though. – sigy Apr 22 '20 at 15:05
  • Yeah, I never figured this one out and ended up ditching the email server. I would go back to it if this was resolved. not much help though. – DanRan Apr 24 '20 at 3:49
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TLDR: This is just a warning and can be safely ignored.

To answer your questions specifically:

  1. Does anyone have any idea what exactly this symlink is doing and who/what is creating it?

    The file itself is just build specific information of the postfix on your system.

    This symlink is made when when you install postfix, so when you got your package manager to installed postfix it would have created this too.

  2. Is it something to worry about?

    No, the reason symlinks are flagged with a warning is because postfix (by default) is run in a chroot in /etc/postfix (in other words it can only access the files in that directory), this is done for security reasons, if you put a symlink in that directory then it can effectively "escape" into another directory.

    In this case it goes to a single (relevant) file so it isn't an issue, but say if you had a symlink that goes to a directory that it doesn't need access to, that's a potential security issue and should be avoided.

  3. How do I get rid of this error message in my postfix check?

    You don't, or rather you probably shouldn't bother, it's important to note the difference between a warning and an error, this isn't an error, it's a warning, an error is something that is broken, a misconfiguration or a bug, and is almost always a problem.

    a warning on the other hand is just something that could be a problem, a lot of the time they can be safely ignored as long as you understand what they mean.

    Sometimes your just going to see warnings in your logs and such from time to time, take time to understand them, sure, but don't take them as the sole sign something is broken.

  4. But what if I really want to remove the warning?

    You can always remove the symlink and copy /usr/share/postfix/makedefs.out to /etc/postfix/makedefs.out, that should stop the warning from appearing, however when you update postfix it's probably going to ask you what makedefs.out to use and using the wrong one could cause issues, I say keep it simple and just ignore the warning.

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