Changing your email server or retiring an email server requires careful planning on your part. Please plan ahead and contact mailto:userservices@uab.eduat the BEGINNING of any plans you have to move e-mail accounts from one computer to another; this will allow time to plan a successful move.
When you consider that existing user account names and their old e-mail address may be stored in many private address books or LISTSERV mailing lists, etc., you will realize that changing a user's e-mail address has the potential to cause problems. Please do not make any assumptions about what DC/NS can do for you; it is best to fully discuss your requirements in advance.
The best course of action depends on your situation. Some possible scenarios include:
- Do your users have an e-mail address that looks like "user@oldmachine.department.uab.edu"?
- Will "oldmachine" and its name be retired?
If you use user account names on the new e-mail server which are IDENTICAL to the old user account names (i.e., msmith will still be known as msmith), it may be possible to move the name "oldmachine" to the new server. Remember, if on the old machine the user was "marvin@oldmachine.department.uab.edu" and on the new machine he is "Marvin.Smith@....", the e-mail system will not know that "marvin" and "Marvin.Smith" are the same person. Messages will bounce saying there is no one named "marvin" at that address.
- Is it possible to create an alias or proxy on the new system?
Some e-mail servers (such as Microsoft Exchange, Unix and certain POP server software) have the ability to create aliases or proxies which can translate old usernames to new. In this way, the user "marvin" can be recognized by the e-mail server software as being the same person as "Marvin.Smith". NOTE: Any use of a proxy or alias is the sole responsibility of the department e-mail administrator; DC/NS does not support this feature.
- Is "oldmachine" still operational? Here are some things that might happen if it is:
- E-mail messages may continue to be delivered to "oldmachine"
E-mail messages addressed to this old machine will continue to be delivered there and held until the user checks for them there. If your users have moved to the new system and are not also checking their old mailbox, they could miss messages.
- Disabling e-mail on "oldmachine" will prevent messages from being held, but may cause another problem.
E-mail on the old machine can be disabled. However, since the machine's name and address still exist, e-mail delivery will be attempted for 3 days. (This is "standard procedure" for Internet E-mail). After three days, the message will bounce back to the sender with a message saying "unable to reach host".
- Can "oldmachine", if still operational, do e-mail forwarding? (sometimes also called setting an alias, or defining a proxy).
- If so, forward each user's account to the new server.
You may be able to set each user's old account to forward to their new e-mail address. This approach allows time for users to inform people of their new e-mail address and request correspondents to update their address books. If you do this, we suggest that you leave the forwarding on for as long as possible.
- If forwarding is not possible and "oldmachine" remains operational, force e-mail to bounce back immediately
Under these circumstances, it is best to rename "oldmachine" and request that oldmachine.department.uab.edu be removed from the DNS. By doing so, e-mail messages sent to the old address will bounce back immediately, resulting in an immediate "host not found" message for the sender. It may be inelegant, but it is better than leaving messages floating for several days or waiting in a place that is never checked.
- Is there a way to avoid these types of addressing problems when changing, moving, or retiring a department e-mail server?
Yes. A good method for avoiding problems when moving e-mail accounts from one machine to another is to use the UAB Electronic Phonebook , which provides e-mail addresses in the form user@uab.edu. Using user@uab.edu as their permanent e-mail address, a user can be sure that their e-mail is being delivered correctly to a consistent address. When there are changes to the user's e-mail server, a one-time update of the "host based e-mail system" entry in the UAB Electronic Phonebook will ensure that their e-mail is directed to the proper location.
- Are you changing an e-mail server IP number but keeping its name the same?
You might do this when, for example, you move the server from one building to another. The potential problem to avoid here is not to lose messages waiting in a queue to be delivered which have already found the (old) IP number. Solution: request that the DNS point to the new IP number a little bit before moving the machine. Change the IP number after the move.