NTL blocking themselves?

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<ntlworld.com #4.0.0 smtp;451 Dynamic IP Addresses See: http://www.sorbs.net/lookup.shtml?82.1.*.*>

Rollocks. Given that the IP address quoted is NTL, and SORBS does report it as blocked, does this mean that NTL are blocking their own servers??

(This was the return from an e-mail I sent FROM my NTL address TO a non-NTL address).

[MrBen]

That listing is correct. The SORBS list that IP is listed on contains IP addresses that are dynamic, which that IP address is.

Are you sending the email using smtp.ntlworld.com? (The ntl outgoing email server) Or are you using your own SMTP server? Have you been able to successfully send to that address before?

Ben

Just realised - that IP address is mine (now blanked out). Yes, I've been able to send to that (non-NTL) address before. Sending via my own SMTP server (MS Exchange). Could it be that my Exchange setup is flakey? (Relaying allowed for local IP (10.*.*.* and 192.*.*.*) addresses only - default Small Business Server instal)

[MrBen]

Hi John,

Ah that would probably explain it. There are lists of dynamic IP addresses such as the one at SORBS because they wouldn't typically be sending email directly out on to the Internet. Users should really be using their ISPs SMTP server (as can be seen in the Additional Information text at SORBS "Dynamic/Generic IP/rDNS address, use your ISPs mail server or get rDNS set to indicate static assignment."). I can only assume that the domain you are sending to has now decided to block email sent from dynamic IPs to try and reduce the number of spam + virus-infected emails received from infected computers. It is not an Exchange configuration problem.

It kind of defeats the object of running your own SMTP server, but as a work around I think you can configure Exchange to pass email on to ntl:'s SMTP server (from where it will be sent out onto the Internet). This should resolve your problem... but also puts you at the mercy of ntl:'s outgoing mail server! I can't remember off-hand how to configure it, but if you need assistance I can look it up on my SBS server tomorrow.

The other route is to maybe try and get the domain at the other end to whitelist your IP address (depends how well you know them though!) but I fear you may eventually run into another domain that also implements this type of email blocking.

Ben

Thanks for that. I'm only using Exchange to familiarise with it, so may just go back to good old Outlook Express for outgoing mail.

[Toto]

Originally Posted by JohnHorb

Thanks for that. I'm only using Exchange to familiarise with it, so may just go back to good old Outlook Express for outgoing mail.

Or, as already stated use ntl smtp address if you still want to experiment

Originally Posted by JohnHorb

I'm only using Exchange to familiarise with it

Gives you the chance to familiarise yourself with setting up a virtual server smarthost relay

Have fun!