[NBLUG/talk] Postfix mail routing

[Christopher Wagner]

I've never done "split delivery" for a domain, where some email 
addresses for a domain go to another server, but I think transport may 
indeed help.  My own mail server either delivers locally for various 
domains, or spam/av filters and relays on to another server for final 
delivery, but it's all based on domain, not individual addresses within 
a domain.

Make sure you read up on Postfix relay setup first and that your server 
is configured correctly for relaying.

I suspect that this MIGHT work, but don't take my word for it (just 
threw this together as a guess):

/etc/postfix/transport:
user1 at example.com    smtp:[yourserver.local]
@example.com    smtp:[foo.gmailsmtpserver.com]

/etc/postfix/relay_domains:
example.com    OK

/etc/postfix/relay_recipients:
user1 at example.com    OK
user2 at example.com    OK

Don't forget to postmap the relevant files before testing!

Also, a quick Google turned up:
https://groups.yahoo.com/neo/groups/postfix-users/conversations/topics/292099
http://serverfault.com/questions/249561/configure-postfix-to-use-external-mx-servers-for-delivery-of-local-mail-if-user
http://postfix.1071664.n5.nabble.com/split-domain-relay-by-default-td56286.html
https://support.google.com/a/answer/2956491?hl=en

Hope this helps.

Chris

On 09/11/2015 01:03 PM, Omar Eljumaily wrote:
> I think this may also solve my problem.  If anybody can say yes or no 
> really quickly, that would be greatly appreciated.
>
> http://www.postfix.org/transport.5.html
>
> Thanks,
>
> Omar
>
>
>
> On 9/11/2015 12:51 PM, Omar Eljumaily wrote:
>> Does anybody know how Postfix will route mail if a user doesn't exist 
>> on one of the local machine's domains?
>>
>> I'm trying to set up GMail for business to handle "split delivery." 
>> Some of the addresses get handled by GMail and some get handled by my 
>> server.  I'm wondering what will happen if my Postfix server sees an 
>> email address that doesn't exist for my domain on that server. This 
>> will happen when local users send mail through it as a relay. Will it 
>> send it along to the proper MX record server, GMail, or will it send 
>> it back an error?
>>
>> I know I can try this, and I will do it over the weekend regardless, 
>> but I was wondering if anybody knows what to expect.
>>
>> Thanks,
>>
>> Omar
>>
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