Postfix Overview - Introduction - SCN Research

Mailbox ownership is controlled by the virtual_uid_maps
and virtual_gid_maps lookup tables, which are indexed with
the full recipient address. Each table provides a string
with the numerical user and group ID, respectively.
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The virtual_minimum_uid parameter imposes a lower bound on
numerical user ID values that may be specified in any virtual_owner_maps
or virtual_uid_maps.
SECURITY
The virtual delivery agent is not security sensitive, provided
that the lookup tables with recipient information are adequately
protected. This program is not designed to run chrooted.
STANDARDS
RFC 822 (ARPA Internet Text Messages)
DIAGNOSTICS
Mail bounces when the recipient has no mailbox or when the
recipient is over disk quota. In all other cases, mail for
an existing recipient is deferred and a warning is logged.
Problems and transactions are logged to syslogd(8). Corrupted
message files are marked so that the queue manager
can move them to the corrupt queue afterwards.
Depending on the setting of the notify_classes parameter,
the postmaster is notified of bounces and of other trouble.
BUGS
This delivery agent silently ignores address extensions.
Postfix should have lookup tables that can return multiple
result attributes. In order to avoid the inconvenience of
maintaining three tables, use an LDAP or MYSQL database.
CONFIGURATION PARAMETERS
The following main.cf parameters are especially relevant
to this program. See the Postfix main.cf file for syntax
details and for default values. Use the postfix reload
command after a configuration change.
Mailbox delivery
virtual_mailbox_base
Specifies a path that is prepended to all mailbox
or maildir paths. This is a safety measure to
ensure that an out of control map in virtual_mailbox_maps
doesn't litter the filesystem with mailboxes.
While it could be set to "/", this setting
isn't recommended.
virtual_mailbox_maps (regexp maps disallowed)
Recipients are looked up in these maps to determine
the path to their mailbox or maildir. If the
returned path ends in a slash ("/"), maildir-style
delivery is carried out, otherwise the path is
assumed to specify a UNIX-style mailbox file.
Note that virtual_mailbox_base is unconditionally
prepended to this path.
virtual_minimum_uid
http://www.porcupine.org/postfix-mirror/virtual.8.html
6/26/01