[Novalug] postfix Q (my domain as a virtual domain)

[John Franklin]

On Apr 5, 2010, at 10:45 AM, Chris Snyder wrote:

> So I just found that if I treat 'example.com' as a completely  
> virtual domain,
> I can get around this problem:
>
> myhostname = mx.example.com
> mydomain = example.com
> mydestination = $myhostname, localhost.$mydomain, localhost
> virtual_alias_domains = example.com
> virtual_alias_maps = hash:/etc/postfix/virtual
>
> Now, all mail addressed to '@example.com' is treated as a virtual  
> domain and
> if an address doesn't exist in the file /etc/postfix/virtual it's  
> ignored
> (whereas, before if the account was in /etc/passwd or /etc/aliases,  
> the
> recipent was considered valid).  On the other hand the only way to  
> deliver
> mail to a local user is to address it to @mx.example.com or send it  
> from
> localhost to localhost. But, this is exactly what I want as the only  
> local
> accounts that should ever recieve mail are the usual Ubuntu utility  
> accounts
> such as mysql, root, etc. and that's all generated internal to the  
> host
> anyway.
>
> So, am I missing anything here? Any major downsides to this?  All  
> the examples
> on the net use the 'add your domain to $mydestination' approach and  
> I can't
> find anything like I've described, but neither can I find anything  
> warning me
> not to do it.


That should work, and I do similar things for some of my domains.  I  
would point out three things:

* Postfix may complain if you put example.com in both mydomain and  
virtual_alias_domains.  I know it will if you put it in both  
mydestination and virtual_alias_domains, but you're getting around  
that with localhost.$mydomain and mx.$mydomain.

* Consider setting virtual_alias_domains to /etc/postfix/ 
virtual_domains and maintaining the domain name list in a file.  This  
will make it easier later on to set up additional virtual domains  
(e.g., gopher.me), even if all they do is forward on a limited number  
of addresses to Gmail.

* A Makefile in the /etc/postfix directory like the one below can make  
managing the mail system a lot easier.

--- Example Makefile ---
all: virtusertable.db aliases.db transport.db
	postfix reload

# I name the virtual_alias_maps 'virtusertable'
virtusertable.db: virtusertable
	postmap /etc/postfix/virtusertable

aliases.db: aliases
	newaliases

transport.db: transport
	postmap /etc/postfix/transport


--- End Example Makefile ---

jf
-- 
John Franklin
franklin at elfie.org
ICBM: 39º 01' 58.4"N 77º 24' 49.6"W Z+84m

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