Postmaster, Who Are You?

by Noel Laam

This is not the head of the Post Office. When you send/receive your e-mail, lots of work has been done behind the scene. The e-mail is scanned for virus, returned with error message if the recipient address is invalid, and answered with auto-reply if the recipient is on leave etc. Do you know who is taking care of all these?

Postmaster is the e-mail system administrator, a valid standard e-mail account that must exist for any standardised system in accordance with the Internet E-mail Standard. In any established organisation like the CityU, the account must be maintained by e-mail specialist(s) and it handles a lot more work than that described above.

Day-to-day Work

The postmaster of CityU ( is responsible for sending error report when an e-mail message fails to reach its recipient. There may be many reasons why it cannot be delivered, and the error report states clearly what causes the problem. On average 500-2000 error reports are generated daily, and a mail header copy of error reports is sent to the postmaster for reference. After studying the pattern of these error reports, the postmaster will take some samples, usually several dozens, and examine them in details. If users have questions on the errors made, they can simply reply to the error report and the postmaster will answer them shortly.

Apart from answering all kinds of enquiries which may reach a dozen a day, handling complaints is also a major job for the postmaster. Complaints may come from different directions (internal or external) and in different forms. Typical ones are concerning e-mail spamming (one mail message to many recipients), e-mail bomb (hundreds/thousands of mail messages to one recipients), mail relay (mainly refers to the malicious mail sent via the CityU server that bears the domain name, network abuse (hacking, unauthorised PC scanning, generating redundant broadcast) etc. Once such complaint is received, the postmaster begins investigation immediately and informs the department(s) concerned. As soon as the cause is found out, a reply will be sent to the person who lodges the complaint to give him/her a brief report of the case, and appropriate actions will be taken if necessary.

Virus is the by-product of modern advanced technology. It is capable of destroying the mail it attaches to, or even the hard disk or system of others if it is spread. In addition to sending virus alert to users whenever a new species or variant is discovered, all incoming and outgoing mail is scanned to ensure it is virus-free before its delivery. However, if virus does exist in any mail, the users (both sender and recipient) will be informed right away and the contaminated mail deleted at once.

The postmaster also regularly monitors the performance of the mail server as well as the mail system to make sure that they are working properly, and delivers auto-reply (e.g. for those who are on holiday) or auto-forward (e.g. for those who left the CityU) messages for users.

What Adds Extra Workloads to the Postmaster?

E-mail is a very handy facility for communication. Exactly because it is so convenient, users tend to use it frequently and sometimes they may cause serious consequences to the e-mail system with their undesirable habits without being aware. As a result, the postmaster has to spend lots of extra effort to rectify the situations. Below are some very common habits of e-mail users that may devastatingly affect the mail server performance:

  • Sending Oversize Mail

Oversize mail not only jams the e-mail path, risks rejection from recipient’s mailbox, causes interruption in transmission, but also induces unnecessary workload for mail server owing to the automatic retries made by the e-mail client software and the need for virus scan.

  • Mass E-mailing

When users initiate mass e-mailing (one mail message to many recipients), it is rather common to find that some e-mail addresses are unreachable. The postmaster will try sending it for 3 days, which means the sending queue will be lengthened, a lot more resources of the mail server wasted, and a warning for each non-delivery given to the sender for his/her information. All these simply add up to the traffic of the e-mail server and will definitely slow down its performance.

  • Leaving Too Much Mail on Server for Too Long

    If a user does not clear the mailboxes regularly, too much mail will be accumulated on the mail server. Apart from exceeding the server quota, this will cause the users to spend longer time to check mail and breakdown/error may result frequently.

  • Storing Too Much Mail in One Mail Box

    It is always recommended not to hold too much mail in one mail box (e.g. the Outbox) so as to limit the damage when a mail box is corrupted. Therefore, it is better for users to categorise the mail into different mail box, or simply save it in other places, say in the hard disk of their PCs.

What's the Difference Between CityU and Other Commercial Postmasters?

As compared to other commercial postmasters like those of Hotmail or Yahoo, CityU postmaster performs a great deal more jobs to ensure the quality services essential for the good system support in our University. To name just a few:

  • sending more alerts to both senders and recipients to warn them of any problems;
  • providing handy internal support to users;
  • maintaining closer relationship with users and hence having better understanding of their needs.

Just now is a brief overview of the work of the CityU postmaster. Users can give a great helping hand by avoiding the undesirable e-mail practices mentioned above, which surely will free our postmaster from the unnecessary burdens to give even better service to all of us.