550 cannot route to sender

[bind at col7.metta.lk]

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
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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