This thread is similar but it didn't solve my problem. I can send emails TO the mailing list from any subscriber domain but it only delivers mail to locally hosted domains. I.E. Gmail, yahoo etc, don't receive the welcome emails or mailing list emails but they can successfully send TO the mailing list and it gets delivered to my local accounts. I've done a postmap /var/lib/mailman/data/transport-mailman and a postmap /var/lib/mailman/data/virtual-mailman with no joy. Error logs don't show anything useful and the maillog doesn't either. Please advise!