-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Alexander Clouter Sent: Monday, March 15, 2010 12:05 PM To: [email protected] Subject: Re: [c-nsp] SMTP
Mohammad Khalil <[email protected]> wrote: > > we have a lot of our customers that are uses SMTP servers other than > our own server which causes the subnet to be black listed > My guess is that you are not cleanly labelling your IP space which means the jobs of the people maintaining blacklists have no idea about the IP usage of your network. As they have no information, and I guess you might ignore your abuse@ mailbox, you get a /24 listing after repeat offences. You need to give your customers IP space clear and up-to-date reverse DNS (PTR) records and where possible detailed WHOIS information on your address allocations. This means that when one of your customers is blacklisted the maintainer has information available to them to make a more targeted listing. I imagine at the moment your WHOIS space probably just says "this /20 is ours", rather than "this /26 belongs to company X which makes up part of our /20 allocation"? You then need to pro-actively monitor (typically blacklisting only occurs if you ignore your abuse@ mailbox to be honest) all the main blacklists and act when you see a listing and deal with the problem. > we tried to block them from accessing any other SMTP server except our > own server using access lists on our core routers it works fine but is > that the optimal solution for that?? is there any other ways to do > that ? > It's a solution, however if you are dealing with business customers you are only likely to end up annoying them. Watch of the following excellent presentation for hints on how to do things properly: --- Just a couple of notes: Hi, Entities such as Senderbase and UCEPROTECT don't even use WHOIS information so that point is irrelevant. Most people now-a-days don't report SPAM to abuse@ addresses because they're either lazy or assume nobody is listening. We're getting into a 'list first, don't ask questions later' scenario which is very frustrating for service providers. -Drew _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
