85 lines
3.2 KiB
Prolog
85 lines
3.2 KiB
Prolog
.TH POSTCONF 5
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.SH NAME
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postconf
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\-
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Postfix configuration parameters
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.SH SYNOPSIS
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.na
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.nf
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\fBpostconf\fR \fIparameter\fR ...
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\fBpostconf \-e\fR "\fIparameter=value\fR" ...
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.SH DESCRIPTION
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.ad
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.fi
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The Postfix main.cf configuration file specifies parameters that
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control the operation of the Postfix mail system. Typically the
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file contains only a small subset of all parameters; parameters
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not specified are left at their default values.
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.PP
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The general format of the main.cf file is as follows:
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.IP \(bu
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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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.IP \(bu
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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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.IP \(bu
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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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.IP \(bu
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A parameter value may refer to other parameters.
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.RS
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.IP \(bu
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The expressions "$name" and "${name}" are recursively replaced with
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the value of the named parameter. The parameter name must contain
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only characters from the set [a-zA-Z0-9_]. An undefined parameter
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value is replaced with the empty value.
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.IP \(bu
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The expressions "${name?value}" and "${name?{value}}" are replaced
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with "value" when "$name" is non-empty. The parameter name must
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contain only characters from the set [a-zA-Z0-9_]. These forms are
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supported with Postfix versions >= 2.2 and >= 3.0, respectively.
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.IP \(bu
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The expressions "${name:value}" and "${name:{value}}" are replaced
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with "value" when "$name" is empty. The parameter name must contain
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only characters from the set [a-zA-Z0-9_]. These forms are supported
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with Postfix versions >= 2.2 and >= 3.0, respectively.
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.IP \(bu
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The expression "${name?{value1}:{value2}}" is replaced with "value1"
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when "$name" is non-empty, and with "value2" when "$name" is empty.
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The "{}" is required for "value1", optional for "value2". The
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parameter name must contain only characters from the set [a-zA-Z0-9_].
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This form is supported with Postfix versions >= 3.0.
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.IP \(bu
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The first item inside "${...}" may be a relational expression of the
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form: "{value3} == {value4}". Besides the "==" (equality) operator
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Postfix supports "!=" (inequality), "<", "<=", ">=", and ">". The
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comparison is numerical when both operands are all digits, otherwise
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the comparison is lexicographical. These forms are supported with
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Postfix versions >= 3.0.
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.IP \(bu
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Each "value" is subject to recursive named parameter and relational
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expression evaluation, except where noted.
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.IP \(bu
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Whitespace before or after each "{value}" is ignored.
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.IP \(bu
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Specify "$$" to produce a single "$" character.
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.IP \(bu
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The legacy form "$(...)" is equivalent to the preferred form "${...}".
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.RE
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.IP \(bu
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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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.IP \(bu
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Otherwise, the order of main.cf parameter definitions does not matter.
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.PP
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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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.PP
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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.
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