Mail being rejected when sent from my SMTP server

[harmonyinfo]

Hi

I am running an SMTP server on my ntl broadband connection. I think this is an OK thing to do according to the terms + conditions.

But I've started finding that some mail servers around the world (eg rr.com and aol.com) are rejecting connections for outgoing email from my smtp server because they don't like my IP address. Reading through their email support bumf it looks like they are rejecting any email sent from an SMTP server running on NTL home user (ie non-fixed) IP addresses (80.5.156.* in my case).

I guess they are assuming that any smtp server on an NTL home IP address is an open relay, but that seems a bit drastic.

Has anyone come across this too? Any solution (apart from going to ADSL with a fixed IP address) or are NTL planning to bring in some kind of fixed IP address?

(I know you can get the fixed IP address for business NTL connections, but that is mega expensive in comparison and I could get an additional ADSL connection with a fixed IP address for less than the difference between NTL home and NTL business prices.)

[Enterian]

Strikes me that some NTL user at some time operated an open SMTP relay on their NTL account and got the entire range placed on a 'block list'.

Not sure if there's anything you can do about it tho:shrug:

EDIT: you could try entering your IP address here (http://www.spamcop.net/bl.shtml) and see if it comes up with anything.

[harmonyinfo]

I wondered if that was it, but the AOL email info says that their smtp servers will refuse any connection from dynamic ip addresses (not sure how they determine that!).

[ic14]

Originally posted by harmonyinfo
I wondered if that was it, but the AOL email info says that their smtp servers will refuse any connection from dynamic ip addresses (not sure how they determine that!).
Have no idea how they can do that. But they have blocked all demon and btopenworld email address for the same (open reley) reason. Meant my dad couldnt email a friend for a while

[Ignition]

Originally posted by harmonyinfo
I wondered if that was it, but the AOL email info says that their smtp servers will refuse any connection from dynamic ip addresses (not sure how they determine that!).

Most static mail servers have names suggesting what they are, IE MTAx.ntlworld.com, mail.whoever.com, smtp.whoever.com.

PC1-wherever4-6.cable.ntl.com looks a bit different. There's just one way of determining it with reasonable accuracy. (BTW for those who might have DNS pointing to their IP this WONT help, on the reverse lookup from IP to name the real ntl DNS will show up).

Obviously there's also blacklisting of ranges of IPs, it's fairly clear which ranges customers are in and which ranges mail servers are in so this can be sorted easily enough.

Sadly a necessity to try and slow down the open relay spamming monkeys.

[El Diablo]

Originally posted by harmonyinfo

I guess they are assuming that any smtp server on an NTL home IP address is an open relay, but that seems a bit drastic.

Has anyone come across this too? Any solution (apart from going to ADSL with a fixed IP address) or are NTL planning to bring in some kind of fixed IP address?


I think that the chances are here, that you haven't been added to an open relay black list, since that would usually involve the blacklisters actually testing your mailserver to see if it relays third party e-mails before being added to the list - they would also tend to mail you to inform you accordingly anyway.

The most likely solution is that you've been added to a Dial-up User List - which covers all IP addresses that are dynamicaly assigned by ISPs to their end users. This way, any mail originating from such an address, that does not get transmitted via the up stream ISPs own mail servers is simply rejected. The only way that you could remedy this would be to amend your mailserver settings so that your mail goes via NTLs mailservers rather than connecting directly to any others...

There are various different mail abuse organisations that allow subscriptions to their blacklist, with MAPS [Mail Abuse Prevention System] being probably one of the more widely used. Whilst I couldn't see any reference to your IP range within the MAPS database, this is probably a good thing, since if you were listed there, your mail would be rejected by a great many more organisations than at present. However, they do offer useful solutions on how to run your mail server on a dial-up network listed in DUL - so if the organisations that are currently blocking your mail use this method independantly, then you should be able to fix it.

MAPS (http://www.mail-abuse.org/)
MAPS DUL (http://www.mail-abuse.org/dul/)
How to run a mail server on a dial-up network listed in DUL (http://www.mail-abuse.org/dul/gateways.htm)

I've also included here (http://www.dnsstuff.com/) a link to the DNS Stuff website which includes a handy look-up tool which can search about 150 spam databases for your IP, this could help you to determine which lists it has been associated with - although it is worth noting that the AOL database is a private one, so look ups will not include any useful references about them.

Anyway, HTH, let us know how you get on! :D


:devsmoke:

[harmonyinfo]

Thanks for the suggestions and links. I'll try some of those out and let you know what the result is.

Jim

[Ian-Highlander]

Had the same problem, in your hosts file, add in entries for the servers affected but give them the IP number of NTL's smtp server.

These are the entries in my hosts file for the AOL servers that I was having problems with.
62.253.162.40 mailin-01.mx.aol.com
62.253.162.40 mailin-02.mx.aol.com
62.253.162.40 mailin-03.mx.aol.com
62.253.162.40 mailin-04.mx.aol.com
62.253.162.40 postman.mx.aol.com

Assuming your SMTP server checks the hosts file before doing a DNS look up (which most do) it will then send all mails to that server to NTL's servers which will then act as a relay as you are an NTL customer and forward them on. Works like a charm.

HTH

Regards

Ian-Highlander