[CentOS] Recommend Mail Server

Christopher Chan christopher.chan at bradbury.edu.hk
Tue Nov 24 05:15:16 UTC 2009


Les Mikesell wrote:
> 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.
>
>   

Just saying that postfix has all the guns needed for a big party.

>> 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.
>
>   

That internal mailer still has to whack something. You would just be 
adding another layer again with the smtp latency. What is with the love 
of uber number of layers?


Exchange...man...blasted thing cannot handle 20 users with multi 
gibibyte mailboxes on a dual Xeon with 3 gibibytes of RAM (HP DL360 [or 
was it a 380...] G3) without choking. Glad I have left that place even 
though all I had left to do was pick the phone and renew contracts and 
the Exchange box was the German team's baby. Kudos Centos and Redhat. :-D


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