Print to a log file:

#!/usr/bin/perl
use strict;
use warnings;
use Test::More;

my @valid   = qw/ foo bar baz /;
my @compare = qw/ foo qux baz /;

my $log_file = 'log.txt';
my $err_file = 'err.txt';

Test::More->builder->output( $log_file );
Test::More->builder->failure_output( $err_file );

is_deeply( \@compare, \@valid, 'My Test' );

done_testing;

__END__
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$ cat log.txt 
not ok 1 - My Test
1..1
$
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$ cat err.txt 
#   Failed test 'My Test'
#   at 1140351.pl line 17.
#     Structures begin differing at:
#          $got->[1] = 'qux'
#     $expected->[1] = 'bar'
# Looks like you failed 1 test of 1.
$
[download]

E-mail from there would be up to you, or maybe there's a module already on CPAN for it.