Some lists are configured that messages are email submitted (sent externally from a mailbox) and then ListManager processes and re-sends it out to the list members. Such mailings from LM to a list could be getting quarantined in users' mailboxes even though DMARC, SPF, DKIM are already set up.
The issue could be DMARC alignment which is a mechanism introduced in DMARC to ensure at least one of the domains authenticated by SPF or DKIM "align with" the domain found in the from header address - the central identity.
ListManager discussion groups are considered a potential sender on behalf of other email addresses, with mail originating from outside each respective ISP. In accordance with these ISPs' recommendation for listservs, the following steps will ensure that mail sent from a member's mail account to a ListManager server's discussion group will be modified so that the sender's address is overwritten with the address of the list itself, thus bypassing the necessary condition for the mail to be sent directly from that ISP's server. You can merge in the sender's name and email address, in order to tell who a message came from in the discussion group, follow the steps below:
- Navigate to Utilities : List Settings : Email Submitted Content and choose the "Header Rewrites" tab.
- Update the "From" field to be the email address of the actual sender as the "friendly name" and the list email address with domain of your ListManager server as follows:
"%%merge inmail_.HdrFromSpc_%%" <%%email.list%%>
- Save changes.
Refer to the following LM 12 User guide section for "Header rewrites" settings: