The aliases file is used to set aliases not set in the directory. In particular, the postmaster alias is a good example. Aliases set in this file will be ignored, if the same aliases exist in the directory. Changes can be activated by issuing the imsimta reload command (or restarting the MTA). Any line that begins with an exclamation point is considered to be a comment and is ignored. Blank lines are also ignored.
Messaging Server provides other facilities for address manipulation, such as the address reversal database and specialized mapping tables. For best performance, however, rewrite rules should be used whenever possible to perform address manipulations. See Chapter 11, Configuring Rewrite Rules.
A physical line in this file is limited to 1024 characters. You can split a logical line into multiple physical lines using the backslash (\) continuation character.
The format of the file is as follows:
user@domain: address (for users in hosted domains) user@domain: address (for users in non-hosted domains. Example: default-domain)
! A /var/mail/ user firstname.lastname@example.org: inetmail@native-daemon ! A message store user email@example.com: mstestuser@ims-ms-daemon