contact with mail support for domain

Hugo Slabbert hugo at
Thu Apr 28 15:37:04 UTC 2016

On Thu 2016-Apr-28 09:48:09 +0200, Piotr <piotr.1234 at> wrote:
>There is a problem with sending emails from employees in 
>domain to some certain domain. Emails in opposite direction pass 
>without problem. No errors, warnings or any other logs at cisco's 
>employees desktop.. We checked popular rbls, spamhauses, senderbase 
>etc. Other domains on the same MX cluster receive emails from 
>I try to get help in many ways ( cisco tac, a few  account managers, 
>channel partners) but without success..
>Big thanks for contact via email:   peter.handke.1966 at
>or any other advice

You've given us damn near zero information to go on.  Are you with Cisco?  
Or managing some of these "certain domains" to which addresses 
cannot send?  It sounds like the latter and that seems more plausible as 
I'd be pretty surprised to find a postmaster sending a vague 
request like this to nanog.  I don't really get how TAC would be involved; 
have you tried postmaster at  Assuming that you *are* the receiving 
side, what logs do you have on this?  What are the names of these "certain 
domains"?  Are they all under the same administrative control / same MXs 
(I'm assuming yes)?

This also seems like something for mailop[1] rather than nanog.  Fair 
warning; they're using Let's Encrypt and are having trouble with the 
rollover, so the cert's expired again.

>best regards,

Hugo Slabbert       | email, xmpp/jabber: hugo at
pgp key: B178313E   | also on Signal

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