USERMAP(7)

NAME
usermap - how postoffice(8) personal aliases work

DESCRIPTION
Personal aliases are a way of slowing down spammers by allowing users on a system to define aliases as needed without having to give them superuser access so they can add entries to the aliases(5) file. Personal aliases are configured in postoffice.cf(5) (the usermap configuration setting,) and may point to aliases(5) -format files in a users home directory. The format of a usermap is pattern:target{,...}, defined as follows:

pattern
    This defines the format of the personal alias. It is a shell-format wildcard, with * matching multiple characters and ~ matching a valid user name. The two standard personal alias formats (user-suffix and prefix-user) can be described as ~-* and *-~, but many other formats are possible.

target
    This is what the personal alias maps to. It can be a simple token like you'd find in the aliases(5) file, but it may also be the token ~, which maps to the matched user name, or ~/filename, which tells postoffice(8) to search the user's personal alias file filename for matching aliases.

    If multiple targets are present, postoffice(8) searches them one by one, stopping when a match is made. Every target except ~/ filename always matches, while ~/ filename only matches if the alias is found in it.

EXAMPLES
To set up personal aliases of the form prefix-user, and have them only exist if they're listed in the file ~/.alias, you would define usermap (in postoffice.cf(5)) as *-~:~/.alias,bounce ( ``bounce'' or any other name that's not a valid user,) and users would have an aliases(5) -format file containing the desired aliases in their home directory.

If, instead, you want all aliases to point at the user except for ones that have been explicitly redefined, usermap would look like *-~:~/.alias,~

BUGS
You may only match ~ once in a usermap.

The personal alias file is treated just like a .forward file, and the user may do anything there that they are allowed in the .forward file.

Users in personal domains are not able to use personal aliases because they have no actual home directories on the machine.

AUTHOR
David Parsons

SEE ALSO
aliases(5), postoffice(8)