Apple Mac OS X Server (Administrator’s Guide) - Manual (Page 407)

Mail Service 407
Creating Additional Email Addresses for a User
Mail service allows each individual user to have more than one email address. Every user has
one email address that is formed from the short name of the user account. In addition, you
can define more short names for any user account by using Workgroup Manager. Each
additional short name is an alternate email address for the user. The additional short names
are called virtual users. For more information on defining additional short names, see
“Defining Short Names” on page 140 in Chapter 3, “Users and Groups.”
Someone whose user account has multiple short names nonetheless has only one mail
account. A user receives mail for all of the user’s short names in one mailbox. The user
cannot set up a different mailbox (or different incoming mail accounts) for each short name.
If a user needs an additional mailbox, you must create another user account.
Note: Mail service does not support virtual domains. For example, mail service cannot
deliver mail for [email protected] to the same mailbox as mail for
[email protected] if example1.com and example2.com have different IP addresses.
Performance Tuning
Mail service needs to act very fast for a short period of time. Mail service sits idle until a user
wants to read or send a message, and then it needs to transfer the message immediately.
Therefore, mail service does not put a heavy continuous demand on the server; it puts
intense but brief demands on the server. As long as other services do not place heavy
continuous demands on a server (as a QuickTime streaming server would, for example), the
server can typically handle several hundred connected users.
As the number of connected mail users increases, the demand of mail service on the server
increases. If your mail service performance needs improvement, try the following actions:
m Adjust how often mail service updates its DNS cache. For instructions, see “Updating the
DNS Cache in Mail Service” on page 397.
m Adjust the load each mail user can put on your server by limiting the number of
connections each user can have on a single IP address. For instructions, see “Controlling
IMAP Connections Per User” on page 386.
m Specify how long you want to allow IMAP mail connections to remain idle before the
connection is terminated. For instructions, see “Terminating Idle IMAP Connections” on
page 387.
m Move the mail storage location to its own hard disk or hard disk partition. For
instructions, see “Changing Where Mail Is Stored” on page 394.
m Run other services on a different server, especially services that place frequent heavy
demands on the server. (Each server requires a separate Mac OS X Server license.)