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From: Jon Giles on 31 Mar 2010 15:02
Victor:

Thanks for the tips. After removing fallback_relay from my main.cf the
loops stopped when the mailbox server is offline, but I still need to set up
the second relayhost.

I don't think a local DNS server would work out for us. The relayhosts may
change their IPs, and so it would be best to use DNS lookups for the two
relayhosts. I tried to get a local bind instance to take two cnames for the
same local relay host name, like:

magma.mailout.local. IN CNAME first.relayhost.com.
magma.mailout.local. IN CNAME second.relayhost.com.

But then named complains about the second CNAME.

And so I have been trying to get your other suggestion to work, but it will
cause mail loops if the mailbox server is offline. Here are the config
excerpts:


transport:
* relay:first.relayhost.com

Main.cf:
Removed relayhost and fallback_relay
Added relay_transport = relay

Master.cf:

relay unix - - n - - smtp (added this
--->)-o fallback_relay=second.relayhost.com

I must be doing something wrong.

Thanks for all the help!

jg


On 3/30/10 1:06 PM, "Victor Duchovni" <Victor.Duchovni(a)morganstanley.com>
wrote:

> On Tue, Mar 30, 2010 at 12:52:28PM -0400, Jon Giles wrote:
>
>> So I set this up in the main.cf file.
>>
>> relay_domains = maildomain1 maildomain2 maildomain3
>> relayhost = to the DNS name of the email archiving service
>> fallback_relay = to the second DNS name of the email archiving service
>
> DO NOT use fallback_relay here. Rather use internal DNS MX records, to
> specify a single relayhost domain name with multiple underlying hosts.
>
>> In a transport file:
>>
>> maildomain1 :[mailboxserverIP]
>> maildomain2 :[mailboxserverIP]
>> maildomain3 :[mailboxserverIP]
>> Etc.
>>
>> Everything works fine, except when we have a problem with the mailbox server.
>> When the mailbox server can not accept email for any reason we get mail loops
>> on incoming mail.
>>
>
> DO NOT use fallback_relay, and the problem will go away.
>
> If you simply cannot configure DNS, use a separate relay_transport,
> with "-o smtp_fallback_relay=..." in master.cf for the dedicated
> transport.



Jon Giles
Network Engineer
The CDM Group 220 East 42nd Street, New York, New York 10017
p: (212) 450-2912

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From: Jon Giles on 31 Mar 2010 15:04
Sorry for missing this.

I have these emails going to a special mailbox and I forgot.

Sorry again, but thanks again for the help and I will try this out today!

jg


On 3/31/10 1:55 PM, "Victor Duchovni" <Victor.Duchovni(a)morganstanley.com>
wrote:

> On Wed, Mar 31, 2010 at 01:28:22PM -0400, Jon Giles wrote:
>
>> Thanks again for the suggestions. Having removed fallback_relay has
>> stopped the loops, but I am still challenged in setting up the failover to
>> the second relayhost.
>>
>> Unless there is something I am missing, using a local DNS server to create
>> the failover isn't an option for me. I can't use A records to point to the
>> relayhosts because the Ips might change over time without my knowledge.
>
> That's why you would use MX records:
>
> localhost zone on MTA DNS server:
> xyzzy.localhost. IN MX 0 primarymx.example.net.
> xyzzy.localhost. IN MX 10 secondarymx.example.net.
>
> main.cf:
> relayhost = xyzzy.localhost



Jon Giles
Network Engineer
The CDM Group 220 East 42nd Street, New York, New York 10017
p: (212) 450-2912

--------------------------------------------------------------------------
Please consider the environment before printing this e-mail.
--------------------------------------------------------------------------

--------------------------------------------------------------------------
Privileged/Confidential Information may be contained in this message. Any strategies and tactics described herein or in attachments are subject to legal and regulatory approval prior to implementation. If you are not the addressee indicated in this message (or responsible for delivery of the message to such person), you may not copy or deliver this message to anyone. In such case, you should destroy this message and kindly notify the sender by reply e-mail. Please advise immediately if you or your employer do not consent to Internet e-mail of this kind. Opinions, conclusions, and other information in this message that do not relate to the official business of The CDM Group shall be understood as neither given nor endorsed by it.

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