I would whole-heartedly concur with this approach - In addition to minimising the work of the script author to write a robust and ruggedly network process, this approach would allow the program to be called 'as-needed' rather than as a daemon process.

Written as a plug-in to a more thoroughly tested and widely used MTA, the script could be called through an /etc/mail/aliases type of pipe such as:

test:          "|/usr/local/bin/myscript"
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With the corresponding script able to process mail received via reading STDIN. eg.

#!/usr/bin/perl -T

use strict;

undef $/;
my $message = <>;
my ($headers, $body) = split(/\n\n/, $message, 2);
$headers =~ s/\n\s+/ /g;

foreach (split(/\n/, $headers)) {
    # ... process headers ...
}
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An excellent suggestion IlyaM++

 

perl -e 's&&rob@cowsnet.com.au&&&split/[@.]/&&s&.com.&_&&&print'