Using smtp.ntlworld.com as smarthost fails

Rich99 · 14-11-2006, 12:12

I have postfix installed on a fresh Ubuntu 6.10 box. The ubuntu config generated a setup that should receive mail by smtp & send it via smtp.ntlworld.com (ie a smarthost). However when I try & send mail (in this case directly from the ubuntu machine using 'mail') I get the following error message:

Nov 13 21:20:06 ubuntu-server postfix/smtp[4950]: B6FE16D818B: to=<me@work.ac.uk>, orig_to=<root@ubuntu-server>, relay=smtp.ntlworld.com[81.103.221.11]:25, delay=7.2, delays=0.01/0/7.2/0.03, dsn=5.0.0, status=bounced (host smtp.ntlworld.com[81.103.221.11] said: 550 relaying mail to work.ac.uk is not allowed (in reply to RCPT TO command))

From my windows machine which is behind the same NAT box, I can send mail from outlook via the smtp.ntlworld.com server with no problems. Any ideas why postfix can't send via the ISP smtp server? I tried swapping postfix for exim4 on this ubuntu machine & the same problem occurred, so it may not be postfix specific. I've posted to the postfix mailing lists in case it could be a postfix problem, but I wondered if anyone knew whether there could be anything on the ntlworld side of things effecting this?

grandmaster · 14-11-2006, 12:17

I can only assume that it is trying to use SMTP.ntlworld as a relay and this is disabled to stop spammers.
I think most isp's and companys disable relays.

Rich99 · 14-11-2006, 12:46

But surely there's no difference between outlook sending via the smtp server & postfix? I'm on the ntl subnet, so it should allow me to send via it surely? Spam prevention would be preventing non-ntl ip's from relaying.

Toto · 14-11-2006, 12:51

Quote:

Originally Posted by Rich99

But surely there's no difference between outlook sending via the smtp server & postfix? I'm on the ntl subnet, so it should allow me to send via it surely? Spam prevention would be preventing non-ntl ip's from relaying.

Check to make sure the from and reply to address are the same.

simbr · 14-11-2006, 13:34

Main reasons for 550 from the ntl SMTP server:

1) You're not on the ntl network
2) You've specified and invalid from: address

I'll assume the first point is moot (although, if you're on wireless it's worth checking that you haven't wandered onto your neighbours unsecured router as I've seen this happen) so it's most likely the latter. The server will accept any email address as sender as long as the format is valid, but if the address ends in @ntlworld.com then it also has to be a valid ntlworld account as well. The server will also not accept a null sender address (<>). The to: address also has to be in a valid format, but I believe the error is slightly different if you mangle the to: address so I think that option can be ignored.

Rich99 · 14-11-2006, 14:05

Quote:

Originally Posted by simbr

Main reasons for 550 from the ntl SMTP server:

1) You're not on the ntl network
2) You've specified and invalid from: address

I'll assume the first point is moot (although, if you're on wireless it's worth checking that you haven't wandered onto your neighbours unsecured router as I've seen this happen) so it's most likely the latter. The server will accept any email address as sender as long as the format is valid, but if the address ends in @ntlworld.com then it also has to be a valid ntlworld account as well. The server will also not accept a null sender address (<>). The to: address also has to be in a valid format, but I believe the error is slightly different if you mangle the to: address so I think that option can be ignored.

Regarding point 1, everythings wired & I'm on the ntl network. regarding point 2, you can see from the log message above that the sender is 'root@ubuntu-server' which is obviously not routeable. Are you saying the sender address has to be 'user@domain.com' for the ntlworld smtp server to accept it? I'll see if I can change that in postix & report back

Toto · 14-11-2006, 15:34

Quote:

Originally Posted by Rich99

Regarding point 1, everythings wired & I'm on the ntl network. regarding point 2, you can see from the log message above that the sender is 'root@ubuntu-server' which is obviously not routeable. Are you saying the sender address has to be 'user@domain.com' for the ntlworld smtp server to accept it? I'll see if I can change that in postix & report back

On the ntl network the sender email address and the reply-to address MUST be the same.

simbr · 14-11-2006, 16:10

Quote:

Originally Posted by Rich99

regarding point 2, you can see from the log message above that the sender is 'root@ubuntu-server' which is obviously not routeable. Are you saying the sender address has to be 'user@domain.com' for the ntlworld smtp server to accept it? I'll see if I can change that in postix & report back

I believe so, yes. I'm not able to access an SMTP server directly from the machines in work since mcafee blocks port 25 so I cannot test those particular circumstances myself at the moment.

sheka · 15-11-2006, 10:56

Quote:

Originally Posted by Toto

On the ntl network the sender email address and the reply-to address MUST be the same.

They aren't in my case....I just relay through smtp.ntlworld.com. Reply address is sometimes my @ntworld.com email address, sometimes a @bigfoot.com address and sometimes something else. It helps as I tend to use different email adddresses depending on what I am doing, posting to forums, internet shopping, personal email, etc. Helps reduce the amount of spam.....

When ever I saw a 550 - it was due to sending mail directly from my PC and not through smtp.ntlworld.com. Some receivers look to see if the IP address that is trying to send is from a dynamic DHCP pool, if it is they can block the request.

Rich99 · 15-11-2006, 13:15

All sorted - it was the name format, just added .com to the end of the hostname & it sent fine. Seems fairly pointless on the ntl side of things - since you can put anything you like there, why does it matter if it's the correct format or not?