.SH SYNOPSIS
-\fBemail-validator\fR [\fB\-har\fR] [\fB-i \fIFILE\fR] [\fB-o \fIFILE\fR] \fI<input>\fR
+\fBemail-validator\fR [\fB\-har\fR] \fI<input>\fR
.SH INPUT
.P
-The \fIinput\fR (default: stdin) should be a list of email addresses,
+The \fIinput\fR (via stdin) should be a list of email addresses,
one per line. Empty lines will be ignored.
.SH OUTPUT
.P
-Valid email addresses will be written to the output file (default:
-stdout), one per line.
+Valid email addresses will be written to stdout, one per line.
.SH DESCRIPTION
.P
-We check the validity of an email address using three techniques:
+Validate an email address using three techniques:
.IP \[bu] 2
-We ensure that the length of local and domain parts is within the
+Ensuring that the length of local and domain parts is within the
RFC-specified limits.
.IP \[bu]
-A regular expression is used to check for invalid characters and syntax.
+A syntax check using a regular expression, or the full RFC 5322
+grammar (see the \fB\-\-rfc5322\fR option).
.IP \[bu]
-We confirm the existence of a MX record for the domain part of the
-address. This is not required; in fact many domains accept mail via
-an 'A' record for e.g. example.com which is used in lieu of an MX
-record. This behavior can be controlled via the \fR\-a\fR flag.
+Confirmation of the existence of an \fIMX\fR record for the domain
+part of the address. NULLMX (RFC7505) records are not accepted. This
+is not required; in fact many domains accept mail via an \fIA\fR
+record for (say) example.com which is used in lieu of an \fIMX\fR
+record. This behavior can be controlled via the \fR\-\-accept\-a\fR
+flag, but note that \fR\-\-accept\-a\fR is ignored for domains that
+have NULLMX records.
.P
These checks are performed in parallel using the number of available
This will set the number of threads to 25:
.nf
-.B $ email-validator -i addresses.csv +RTS -N25
+.B $ email-validator +RTS -N25 < addresses.csv
.SH OPTIONS
Accept an 'A' record for the domain instead of requiring an MX record
(the default).
-.IP \fB\-\-input\fR,\ \fB\-i\fR
-Specify the input file containing a list of email addresses, rather
-than using stdin (the default).
-
-.IP \fB\-\-output\fR,\ \fB\-o\fR
-Specify the output file to which the good addresses will be written,
-rather than using stdout (the default).
-
.IP \fB\-\-rfc5322\fR,\ \fB\-r\fR
Verify addresses against RFC 5322 rather than a naive regular
expression. This is much more lenient than the default.