- Block destination port 25. This prevents bots from sending
email directly to the victims MXes. No one wants to (must not) run an MTA in a dialup range: Many MXes dont accept emails orginating from dial-up rages. No one wants to (must not) run an MX in a dial-up range. The risk of delaying or losing email due to a IP change is not acceptable. And what if the successor of the IP runs an MX which accepts all Mail..?
thats right. Telia has started as first ISP blocking Port 25 years ago...
Given the second point is OK, this whole blocking thing this not a bad idea. And its not that hard to configure fetchmail/authenticated relaying to a smarthost for geeks who want to run their own email infrastructure (in contrary it adds som salt to the whole soup ;)
Why not sell some fixed IPs, to customers who want use their own mailserver ? If i receive a request from such a user, that has a dyn IP, i tell him to buy a static one, because of full control and exclusion of DUHL. Furthermore the customer is self responsable, if a IP Adress in his range will be listed. Complaint Mails are also directly sent to the owner of the IP, so the Abuse Team don't need to work on such cases.
Greetings
Daniele Ladu