On 6/28/2012 5:36 AM, James B. Byrne wrote: > Thank you for your assistance. I am not concerned that the advice I > receive is wrong. My limited experience with Postfix simply makes it > difficult for me to grasp the entire meaning and implications of what > I am told. > > Perhaps this would be clearer to me if you would be so kind as to give > me the canonical use cases for virtual_aliases and for virtual_domains > insofar as Postfix considers them. Why is the latter superior to the > former in my situation? > > I have finally managed to get the desired behaviour out of Postfix > using virtual_aliases and before I discard that effort for another > approach I would like to have some idea what the benefits would be. > >
Nickle tour expanding on ADDRESS_CLASS_README: local domains listed in mydestination is basic functional email, simple to set up for sites with modest requirements. Each recipient must have a unix account or be an alias for a unix account. There is no namespace separation; a username is presumed to be the same recipient regardless of domain. Given "mydestination = example1.com example2.com", mail to t...@example1.com goes to the same mailbox as t...@example2.com. * Local delivery does allow .forward file processing and delivery to a command, which are not supported with other postfix delivery agents (third party delivery agents may provide their own substitute). virtual_alias_maps is a general-purpose recipient->recipient(s) mapping mechanism. *ANY* recipient address, internal or external, can be rewritten with this table; the domain does not need to be specified in virtual_alias_domains to be rewritten. virtual_alias_domains is for *domains* (not simply users) that are virtual. When a domain is declared in virtual_alias_domains, all recipients in that domain must be listed in virtual_alias_maps, and *must* be rewritten to a different domain, presumably their "real" domain. A typical use for this is a "vanity" domain mapped to a "real" domain, or an old/unused domain mapped to the current domain. virtual_mailbox_domains / virtual_mailbox_maps is for the typical "hosted" domain with recipients that may or may not be actual unix users and the possibility of many separate domains coexisting on the same server. Delivery to the mailstore may be either the built-in virtual(8) transport, or a third-party delivery agent such as cyrus, maildrop, or dovecot. In the case of a third-party delivery agent, virtual_mailbox_maps is simply a list of valid recipients and not used by postfix during delivery. t...@example1.com is a different mailbox than t...@example2.com relay_domains are domains postfix is the MX for, but the final delivery is on a different server. Typically used when postfix is the MX gateway for an internal mail server. There is considerable overlap with all these, and you can eventually create a working system regardless of which address class you choose. However, picking the class that most closely matches your application will make both initial configuration and future maintenance far easier. -- Noel Jones
