550 cannot route to sender

Joseph S D Yao jsdy at cospo.osis.gov
Tue Nov 16 14:48:23 UTC 1999


On Sun, Nov 14, 1999 at 01:04:55PM +0600, bind at col7.metta.lk wrote:
> Hi all,
> 
> I have set up Qmail on "metta.lk" (204.143.107.46)
> and use autoturn to get my mail to "col7.metta.lk" (172.16.1.1)
> Everything works quite well.
> 
> To some domains I get messages like the below returned by Mailer Deamon.
> 
> Is this a DNS problem on my machine
> or is it because I am on local IPs
> 
> If you have the time please do a "dig" at my server
> to see it If have anything wrong in the DNS.
> it works all well from my side, but perhaps not from outside.
> 
> A suggestion on how to overcome it would be much appriciated
> 
> Jacob
> -----------------------------------------------------
> 
> 130.88.200.93 failed after I sent the message.
> Remote host said: 550 rejected: cannot route to sender
> <sltp at col7.metta.lk>
> 
> can one route to 172.16.1.1 (col7.metta.lk) as a local IP
> 
> 131.111.8.70 failed after I sent the message.
> Remote host said: 550 rejected: cannot route to sender
> <sltp at col7.metta.lk>
> 
> Connected to 128.135.12.12 but sender was rejected.
> Remote host said: 501 <sltp at col7.metta.lk>... Sender domain must exist

I am afraid that I have not had time to take a 'dig' at your server.
However, I can suggest what might have happened.

Private internet addresses, such as col7's, should never be visible in
DNS to the general Internet.  It looks like the remote host found the
address for col7, and tried to send it directly.  Of course, it failed.
This also suggests that either you do not have a publicly visible host
with an MX record pointing to it for col7.metta.lk (or *.metta.lk, not
advised to prevent mailings to random non-existent hosts), or you do
have such a host and record and the remote host ignored it.

Note that an MX record for metta.lk would not have sufficed in this
case, since the address is "... at col7.metta.lk".

Until you get this fixed, OBTW, you may not want to have your return
address be "... at col7.metta.lk".

-- 
Joe Yao				jsdy at cospo.osis.gov - Joseph S. D. Yao
COSPO/OSIS Computer Support					EMT-B
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