[CentOS] Large scale Postfix/Cyrus email system for 100, 000+ users

Tue Oct 23 16:46:28 UTC 2007
Chris Geddings <chris.geddings at duke.edu>

On Oct 23, 2007, at 12:28 PM, Matt Shields wrote:

> Forward's aren't acceptable.  There is a way to do it with the
> transport function and lmtp on a account by account basis.  I'm
> looking for real world configs from someone that has this working.

Not condoning, but providing some links:
http://middleware.internet2.edu/dir/docs/ldap-recipe.htm#E-MailRouting
http://www.postfix.org/LDAP_README.html#example_virtual

The transport function will tell you how to deliver to a particular  
server, but I'm not
sure you are going to get the kind of efficiency you probably want  
thinking of the
user account to server mapping as part of the transport functions,  
though suggestions
have been made that will meet that way of thinking.

Regardless what method you use to generate the maps, be it mysql,  
ldap or flat file,
you will want the maps available to each edge host on the box  
themselves, so either
storing copies of the flat files, a local copy of the mysql database  
or a local a local directory
(none of them being the masters, more functioning like caching only  
name servers.)  I'm partial
to flat files for smaller maps and LDAP for larger ones, but there  
are arguments all the way around,
some of which depend on local admin familiarity with whichever tech.

> Forward's aren't acceptable.  There is a way to do it with the
> transport function and lmtp on a account by account basis.  I'm
> looking for real world configs from someone that has this working.
>

Depending on how you define forwards, it is not going to be possible  
for you to not have forwards,
unless you have a large number of domains pointing directly at your  
delivery point servers and have
only a certain number of domains per individual server.

--Chris