We're looking at the pros and cons of Mailman/Distribution Lists and putting aside everything else we're looking at, we're interested in single-copy message storage.

If a message is sent from Zimbra >(single to: address)> Mailman >(many list members)> Zimbra, is this stored as a single file and hardlinked? I would assume so since there are multiple recipients and one message-ID. Please let me know if I'm wrong.

We've found ourselves having issues with very large lists (our All list for example) where Zimbra would seem to hang on a particular message for a very long time, as if it were waiting on access to a particular user's mailbox. If enough list mails were coming through, eventually all the threads would seem to end up blocked and waiting. We've gotten around this for now by setting mailman to deliver messages with a max of 25 recipients, but assuming single-copy does work for Mailman messages, this obviously means we're chewing more storage now.

I was wondering if anyone else had experienced similar issues with either Mailman or DL and whether anyone could confirm the single-copy status of Mailman mails.

Thank you,