[CentOS] Recommend Mail Server

[Les Mikesell]

Christopher Chan wrote:
>  
> Ian pointed how he needs to 'replicate' a local copy of user 'accounts' 
> from Exchange so that he does not kill Exchange. I just pointed out that 
> this sort of thing can be done also for sites with a very large user 
> base that will want something that is more efficient that Berkeley DB. 

There might be a few places big enough where using cdb vs. the built in bdb for 
the virtuser table would matter.  But very few.

> You can chain lookups in postfix. Check cdb, then check 
> mysql/postgresql. If the account exists in the cdb, then there is no 
> need to check mysql/postgresql. So essentially only non-existent 
> addresses and recently created addresses will result in hits to 
> mysql/postgresql. This is not a work around. This is performance 
> enhancement. Whacking a local cdb will be faster than whacking a 
> mysql/postgresql database. Geez.

If you have a reasonably fast internal mailer you can just let mimedefang on 
your external relay check against it with smtp in real time.  Exchange isn't one 
of those, though.

-- 
   Les Mikesell
    lesmikesell at gmail.com