Some emails may not be going through LM and you see errors such as the following:
550 5.7.0 Email rejected per sender firstname.lastname@example.org Organization DMARC policy and the error
<-- 550-Please turn on SMTP Authentication in your mail client, or login to the
<-- 550-IMAP/POP3 server before sending your message. lists.ncsl.org
<-- 550-[XXX.XXX.XXX.XXX]:40795 is not permitted to relay through this server
<-- 550 without authentication.
If these errors are for discussion lists for email submitted content messages, please review the following article for DMARC and these types of lists: