Wietse,

That safety net of yours should be a fantastic tool, and I congratulate you
for the idea and implementation. Also, I am happy for using postfix, it
seems it is the only smtp service with so much valuable and good
contributions from the developers and contributors net.

Best regards,
---
Fernando Maciel Souto Maior



On Wed, Oct 1, 2014 at 12:57 PM, Wietse Venema <[email protected]> wrote:

> I am implementing a safety net for incompatible Postfix configuration
> changes.  After a Postfix upgrade, this will allow you to keep
> running Postfix with the historical default settings, during which
> time Postfix will log all uses of any old default value that will
> be affected by an incompatible change.
>
> Examples:
>
>     master.cf: line 72: using legacy default setting chroot=y
>
>     using legacy default setting append_dot_mydomain=yes to rewrite
>         "foo" to "foo.example.com"
>
>     using legacy default setting smtputf8_enable=no to accept
>         non-ASCII address "[email protected]"
>
> Once you have run Postfix for some time, you know if any main.cf or
> master.cf setting needs to be updated (set explicitly to old default
> value) before you can turn off these checks. More on that below.
>
> The safety net is controlled with one configuration parameter:
>
>     name: compatibility_level
>     default: 0 (zero)
>
> At this time, no Postfix system has a compatibility_level setting
> in main.cf, therefore it will be zero.
>
> There is also an internal compatibility level that increments by 1
> with each incompatible change. With the next Postfix snapshot, this
> internal level will be 1.
>
> The next time you upgrade Postfix, the main.f compatibility level
> will be zero, which is smaller than the internal level of 1.
>
> This turns on a couple things:
>
> - Use backwards-compatible default settings so that Postfix keeps
>   working as before.
>
> - Log the above messages when Postfix is actually using any of those
>   backwards-compatible default settings. This will show whether your
>   site depends on the old defaults.
>
> Finally, you set the parameters explicitly that must stay at their
> historical value, and configure "compatibility_level = 1" in main.cf.
> This turns off the checks and warnings.
>
>         Wietse
>

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