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Postfix configuration parameters
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\fBpostconf\fR \fIparameter\fR ...
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\fBpostconf -e\fR "\fIparameter=value\fR" ...
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The Postfix main.cf configuration file specifies a small subset
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of all the parameters that control the operation of the Postfix
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mail system. Parameters not specified in main.cf are left at their
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The general format of the main.cf file is as follows:
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Each logical line has the form "parameter = value".
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Whitespace around the "=" is ignored, as is whitespace at the
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end of a logical line.
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Empty lines and whitespace-only lines are ignored, as are lines
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whose first non-whitespace character is a `#'.
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A logical line starts with non-whitespace text. A line that starts
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with whitespace continues a logical line.
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A parameter value may refer to other parameters.
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The expressions "$name", "${name}" or "$(name)" are
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recursively replaced by the value of the named parameter.
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The expression "${name?value}" expands to "value" when
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The expression "${name:value}" expands to "value" when
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When the same parameter is defined multiple times, only the last
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instance is remembered.
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Otherwise, the order of main.cf parameter definitions does not matter.
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The remainder of this document is a description of all Postfix
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configuration parameters. Default values are shown after the
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parameter name in parentheses, and can be looked up with the
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\fBpostconf -d\fR command.
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Note: this is not an invitation to make changes to Postfix
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configuration parameters. Unnecessary changes can impair the
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operation of the mail system.