Spamhaus PBL on static IP

[#1]

Hi all, I've seen one or two posts about this here and no real solutions offered that would work for me.

I have a mail server at the end of a Plus.Net assigned fixed IP and every six months or so I find it has been re-added to the Spamhaus PBL. We have had the same IP address for a couple of years now and the error given by Spamhaus alludes to the IP address being in a range which Plusnet have allocated for dynamic users.

Is there a solution to this? (reactively unblocking with Spamhaus every few months isn't a solution, and relaying through plusnet's mail server is not really something I'd want to do if it can be avoided). My thinking is that business grade broadband with fixed IPs registered to us with RIPE shouldn't cause a spam filter to trigger.

[#2]

To run your own mail server from a Plusnet connection not to flag up as spam in this way, you'd need to use relay.plus.net as a smart host. Alternatively make sure that your mail is set up to be "authenticated" as that may work instead.

[#3]

So, either relay (which I didn't really want to do) - or something else that we've already done.... How's about you guys just stop being lazy and tell Spamhaus what IP addresses in your range have been allocated as fixed to clients like us?

[#4]

As far as I'm aware this is a process across the board whether you've got a dynamic or static IP, or you're a business or residential customer. Apologies for the inconvenience caused.

[#5]

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@Gandalf wrote:

To run your own mail server from a Plusnet connection not to flag up as spam in this way, you'd need to use relay.plus.net as a smart host.

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That shouldn't be necessary if you have a static IP address - I ran a mail server for many years using a Plusnet connection without using a smart host.

I believe the problem is that a lot of the static IP addresses Plusnet provide now are reserved dynamic addresses that don't change between re-connections rather than static IP addresses, and as such do appear on the PBL as dynamic addresses. It may help to set a rDNS entry to match your mail server, and then request that address to be removed from the PBL - it is less likely to be re-added once it has a rDNS entry.

Another solution is to use a L2TP connection to AAISP (or similar service) so that you have true static IP addresses (IPv4 and IPv6), and I have used that since moving to a 4G  connection. Another alternative is to move to an ISP that is better set up for business users.

[#6]

As far as I’m aware our static IPs are still genuinely static and haven’t changed in the time I’ve worked here. They’re allocated from different pools to dynamic IPs.

It’s possible the issue’s with the authentication setup of their mail server when sending emails, if for one reason or another relay.plus.net can’t be used as a smart host. 

[#7]

Technically, the SpamHaus PBL doesn't just list dynamic addresses - it lists all addresses that it considers should not directly send mail. These can be static or dynamic, although the latter are generally considered bad as historically they have been widely abused.

SpamHaus have two mechanisms for determining whether an address block should be sending mail:

1. they are informed by the owner of the block - not all ISPs do this
2. they use heuristics to spot blocks that have the characteristics of dynamically assigned addresses - this includes examining the rDNS. The Plusnet static address blocks tend to match these heuristics.

It is straightforward to have single address to be removed from the PBL, but that can be temporary if the heuristics pick it up again later. That's why setting a rDNS that matches the machine running SMTP can help