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I'm facing a strange problem. I'm getting a recipient rejected on a SMTP server only from inside an OpenVZ container, while from the physical server everything works fine.

Here's an example of a telnet test connection while inside a routed Vz container:

telnet mx.adomain.com 25
[...]
rcpt to: username@adomain.com
550 5.1.1 <username@adomain.com> recipient rejected
Connection closed by foreign host.

While the same telnet connection from a physical server works as expected. The problem arises only with the mx.adomain.com server, on other SMTP servers like for example gmail.com everything works fine even inside the virtual container.

I've checked and the IPs of the Vz containers don't belong to any blacklist. More strange is that until 3 days ago everything worked fine.

Any ideas?

Atropo
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1 Answers1

2

Because you get delivery from one machine but not the other, I'd assume that the remote MTA is being reticent or lying outright on the 'recipient rejected' bit - qmail, for instance, does it all the time. So possible causes would be:

  1. One client is on a BL, the other is not.
  2. One client not in the SPF record for the domain
  3. Something fishy in the smtp chat "[...]" (e.g. wrong helo line)
  4. Container has "wrong" reverse resolution or no reverse resolution
  5. Assorted local policies at the receiving end

NOte that points 1 and 2 assume the host and the container talk from different IPs (no NAT).

Best bet would be asking to the postmaster at the receiving end - assuming he/she's listening.

Cheers,

Alien Life Form
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