The way you are going about this (shelling out from perl to run perl) is not only crazy and inefficient but it's also unmaintainable as you are currently finding out. Here's the answer to your question but don't you ever write code like this for any real purpose.

use strict;
use warnings;

use Test::More tests => 1;

my $want = 'aa9957b8d673c62eb1e836cbfcf09719ca41e6e3bf960bba98e74289b8
+8b66fb';
my $email = 'BOK_NEPA@hotmail.com';

# XXX Really awful horrible code to test starts here
my $SENDVAR1 = qq(perl -MDigest::SHA=sha256_hex -E 'say sha256_hex(q/$
+email/)');
my $email_SHA256 = qx($SENDVAR1);
# XXX Really awful horrible code to test ends here

chomp $email_SHA256;
diag "Command is >$SENDVAR1<";
is $email_SHA256, $want;
[download]

See also How to ask better questions using Test::More and sample data and the Basic debugging checklist.