Hello out there! I'm new at company and have fair experience in linux mainly redhat and fedora. Now I have tasked to figure out the mail server ubuntu, running pegasus mail system, which users are saying that some mails are not arriving them or not reaching them from the senders. Now my question is where do I start to troubleshoot this problem. When I contacted some of the senders there is no undelivered error messages they recieved after sending mails. What should I do, am afraid need not to mess up with the system.