Are NTL server/netblock IPs blacklisted?

daemon · 21-11-2006, 14:04

Hi,

Can anyone confirm my suspicion that some NTL server and/or netblock IP addresses have been listed in blacklists somewhere?

I am, at present, unable to send e-mail to aol.com addresses and others like knujon.com.

Typical NTL server bounces are:
Nov 21 11:44:06 router postfix/smtp[52284]: 02DC5102F61: to=<contact@knujon.com>, relay=smtpin.ntlworld.com[81.103.221.10]:25, delay=2.3, delays=0.03/0.06/2.1/0.11, dsn=5.0.0, status=bounced (host smtpin.ntlworld.com[81.103.221.10] said: 550 relaying mail to knujon.com is not allowed (in reply to end of DATA command))

This bounce was solicited by my server which is hosted on a NTL broadband connection. It's been working perfectly until recently.

Regards,
Neil Darlow

Stuart · 21-11-2006, 14:08

Quote:

Originally Posted by daemon

Hi,

Can anyone confirm my suspicion that some NTL server and/or netblock IP addresses have been listed in blacklists somewhere?

I am, at present, unable to send e-mail to aol.com addresses and others like knujon.com.

Typical NTL server bounces are:
Nov 21 11:44:06 router postfix/smtp[52284]: 02DC5102F61: to=<contact@knujon.com>, relay=smtpin.ntlworld.com[81.103.221.10]:25, delay=2.3, delays=0.03/0.06/2.1/0.11, dsn=5.0.0, status=bounced (host smtpin.ntlworld.com[81.103.221.10] said: 550 relaying mail to knujon.com is not allowed (in reply to end of DATA command))

This bounce was solicited by my server which is hosted on a NTL broadband connection. It's been working perfectly until recently.

Regards,
Neil Darlow

I suspect it's because NTL don't allow relaying via their SMTP servers.

daemon · 21-11-2006, 14:45

Quote:

Originally Posted by Stuart C

I suspect it's because NTL don't allow relaying via their SMTP servers.

Me sending e-mail to aol.com and knujon.com addresses is legitimate relaying (NTL customers should be able to send mail through NTL's servers) and has always worked before. It's more likely that the bounce message is misleading and the cause lies elsewhere.

Regards,
Neil Darlow

dev · 21-11-2006, 15:21

is the from email set to a valid email? (maybe an ntlworld.com one)

Stuart · 21-11-2006, 15:29

Quote:

Originally Posted by daemon

Me sending e-mail to aol.com and knujon.com addresses is legitimate relaying (NTL customers should be able to send mail through NTL's servers) and has always worked before. It's more likely that the bounce message is misleading and the cause lies elsewhere.

Regards,
Neil Darlow

I never said it wasn't legitimate. It is, however, possible that NTL have reconfigured their SMTP servers to block all relays.

daemon · 22-11-2006, 10:27

Quote:

Originally Posted by Stuart C

I never said it wasn't legitimate. It is, however, possible that NTL have reconfigured their SMTP servers to block all relays.

That seems to be the case. A silent, and major, change of policy.

I manually conversed with smtp.ntlworld.com using telnet and it appears that mail from @ntlworld.com is accepted but anything from @yourdomain is bounced with Relaying not permitted.

This is a big problem for those of us who run our own mail server and deliver via NTL's SMTP servers for destinations that block mail from dynamic IP addresses.

daemon · 23-11-2006, 10:12

Having alerted NTL's postmaster to my situation it appears to be resolved as of this morning.

I would like to think that there was just a problem with my netblock not being authorized to relay via NTL's servers but the fact that my domain addresses weren't allowed, and ntlworld.com ones were, suggests otherwise.

Perhaps it was a decision made in haste and, on reflection, reversed. Anyway all appears to be in order now.