This example works fine
$SENDVAR1 = q(perl -MDigest::SHA=sha256_hex -E 'say sha256_hex(q/XXXX/)');
my $email_SHA256 = print qx($SENDVAR1);

This doesn't work:
$SENDVAR1 = q(perl -MDigest::SHA=sha256_hex -E 'say sha256_hex(q/$EMAIL_IN/)');
my $email_SHA256 = print qx($SENDVAR1);