HPCC-9256 Email module in std library missing import

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #4350 from richardkchapman/email-import

HPCC-9256 Email module in std library missing import

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>