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List:       postfix-users
Subject:    Re: Making a shadowing server?
From:       Noel Jones <njones () megan ! vbhcs ! org>
Date:       2008-07-30 15:06:42
Message-ID: 48908382.8090503 () megan ! vbhcs ! org
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Johan Andersson wrote:
> Hi,
> 
> New as I am to postfix, I have been trying to find some answer to my 
> current dilemma...
> 
> Incoming mails to the domain(s) hit postfix MTA's with antivirus and 
> anti-spam
> these send emails on to a mail storage, today an old iPlanet server 
> (clustered)
> 
> All users, aliases and other user data are stored in LDAP, as per the 
> iPlanet model.
> The user base is updated daily.
> 
> Now hey want another server, not iPlanet or JES, most probably a 
> linux/postfix one
> to shadow the main server, getting a copy for every mail going to the 
> iPlanet server
> to also go to the new server, making it a possible replacement system 
> for the original
> one in case of catastrophic failure of it.
> 
> I have been looking at the options like always_bcc and the likes, and 
> although the
> recipient_bcc_maps looks usable, it would mean maintaining a huge list 
> which will
> change a lot.
> 
> is it possible to just make postfix edge MTA just send every mail it 
> sends on to the old
> mailserver also sent to the new mailserver, regardless of what user it 
> is? Valid users
> are checked already at the edge MTA anyway.
> 
> i.e.
> 
> Sending Host
>   |
>   |
>   |
> Edge MTA with AntiSPAM/AntiVirus (gateway?)
>   |\
>   |  \__ new Mailserver (new.example.com)
>    \
>      \__ old MailServer (old.example.com)
> 
> Both servers being configured to receive mail for the same domains and 
> storing
> the mails in whatever fashion that product uses. Both using the same 
> LDAP authentication
> data, but only the old one doing forwards and vacations and such... (for 
> now)
> 
> I know this is a strange way to do things, but this is what this 
> customer wants at this time
> so I am checking if it is even possible to do it without getting in to 
> more administrative work
> then need be, maintaining a recipient_bcc_maps that is up to par seems 
> like a bit to much
> work to me.
> 
> it would have been great if one could just have listed two relays to the 
> domain and gotten
> it to send a copy to each one.
> i.e. /etc/postfix/transport
> 
> example.com  smtp:[old.example.com], [new.example.com]
> 
> or something similiar...
> 
> Anyone has any insight to as how this might be accomplished?
> 
> /J. Andersson
> 
> 

The SMTP protocol (and postfix) delivers one recipient to 
exactly one destination; to add a second destination you need 
to add another recipient.

recipient_bcc_maps is the right tool for this.  Check the list 
archives for examples, this is a fairly common question.  This 
is usually referred to as mail archiving.

Note that while this will duplicate incoming mail to the 
second server, no one ever deletes mail from it, and it won't 
contain internal to internal mail if that mail doesn't go 
through postfix.
So make sure the customer understands it won't be an exact 
copy "instant replacement" in case of catastrophic failure.

-- 
Noel Jones
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