BGP hijack from 23724 -> 4134 China?

Jeroen van Aart jeroen at
Fri Apr 9 20:01:43 CDT 2010

Patrick Giagnocavo wrote:
> This DID actually bite my company about 3 years ago.
> A customer went to China (usually in NYC) and could not send email
> through the mail server because they were using POP-before-SMTP instead
> of the mail submission port .

The problem did not lie with blocking IPs. But with offering a flawed 
service such as pop before smtp to begin with. I know many ISPs/ESPs 
still do, much to my chagrin. The only way to submit email should be 
port 587 with TLS encryption, 3 years ago one could be forgiven for 
offering deprecated (*) port 465 with SSL, but not anymore (msoft 
clients have been fixed).

* urd             465/tcp    URL Rendesvous Directory for SSM

More information about the NANOG mailing list