* fix: make bulk_email send email task handles a retryable exception According to bulk_email and SMTP doc, when an error code is between (400-499) it can be retried after sometime, this commit adds a new type of exception called SMTPSenderRefused, so it can be retried **if** it's code fails under above constraint. * test: add test to handle SMTPSenderResfused Co-authored-by: Justin Hynes <jhynes@edx.org>
LMS (Learning Management System) -------------------------------- This directory contains code relating to the student portal for edX.