Re: [exim] Help with a relay configuration

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Author: Odhiambo G. Washington
Date:  
To: mbneto
CC: exim-users
Subject: Re: [exim] Help with a relay configuration
* On 18/01/07 11:09 -0400, mbneto wrote:
| Hi,
| 
| I am trying to setup one machine to act as a 'special' mx/relay.
| 
| This machine would
| a) receive the connections (I'd set up as my MX for my hosted domains)
| b) use DNSBL, SpamAssassin to determine if the message should be delivered
| c) discover if the recipient is routeable (is 'exists locally' or is a
| remote address)
| d) deliver de message to the remote address
| 
| I use 'locally' because I'd not actually have the mailbox local, instead the
| MX would relay the message to a remote machine which will actually have the
| maildir.
| 
| the algorithm
| - resolve the recipient's address
| - is it local? (i.e the @domain is considered local)
| - yes
|     - does it exists?
|        - yes. relay to remote server
|        - no. return message


Up to that point, I see like this is a server that receives mail for your
domain, but then delivers mail to an internal server, i.e. a hub host.
I believe the default exim behaviour will check what you want, if you
keenly use the "verify = recipient/callout".
However you also need a manualroute router to deliver the mail to the
internal server once it's verified.


| - no
|     - deliver (or try to) to the MX server of the domain


MX of which domain? This sounds like being an open relay to me. The
above steps handle mail for your "local" domains. Everything else should
be rejected, unless I am missing the point. If by "the MX server of the
domain" you mean domains that "this host is mx for", then fine... just
put those domains in relay_to_domains.


| The MX server would be located in a facility with a "lot" of bandwidth and
| the remote one in another facility with a smaller bandwidth.
|
| I already know how to set up a MX server with DNSBL and spamassasin. I am
| having problems trying to figure out how to find if the user exists and how
| to set this 'fixed' relay for those cases.
|
| Any ideas?


Sounds like what I have explained above.

1. "find if the user exists" == recipient callout
2. "howto set this 'fixed' relay for those cases" == relay_to_domains

You are responsible for handling mail for those +relay_to_domains?



        cheers
       - wash 
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