UCEPROTECT-2 and 3 aren't blocklists, they're reputation lists. Anyone straight blocking off those lists has most likely misconfigured their filtering and should expect to be missing mails.
Use of Level 3 for blocking is recommended only if you are a HARDLINER and you want to cause service providers and carriers that have spammer / abusive clients to be quickly and effectively blocked and it does not matter to you if regular email is also occasionally rejected.
> https://www.uceprotect.net/en/index.php?m=3&s=5
This has been the subject of hot debate on one of the popular mailing list operator's lists, and the providers that find themselves in Level 2/3 reliably are working on strategies to deal with that but it becomes complicated to do anything that affects thousands of customers. You'll find the providers that aren't on these lists are the ones that have an equally strict policy for allowing outbound Port 25 from their customers and a severely punitive abuse desk.
IMO, I run a personal mail server and deliver directly and if my mail is rejected or lost then I use another mechanism to contact that person (usually telephone) and inform them of the failure. I also provide usable feedback to senders for why I may have chosen to reject their message. And when it really matters, I also have a relay I can use for troublesome transports.
NOTE: By using Level 2 blocking, be prepared to lose a few mails too. DO NOT BLAME US, YOU HAVE BEEN FOREWARNED! > https://www.uceprotect.net/en/index.php?m=3&s=4
Use of Level 3 for blocking is recommended only if you are a HARDLINER and you want to cause service providers and carriers that have spammer / abusive clients to be quickly and effectively blocked and it does not matter to you if regular email is also occasionally rejected. > https://www.uceprotect.net/en/index.php?m=3&s=5
This has been the subject of hot debate on one of the popular mailing list operator's lists, and the providers that find themselves in Level 2/3 reliably are working on strategies to deal with that but it becomes complicated to do anything that affects thousands of customers. You'll find the providers that aren't on these lists are the ones that have an equally strict policy for allowing outbound Port 25 from their customers and a severely punitive abuse desk.
IMO, I run a personal mail server and deliver directly and if my mail is rejected or lost then I use another mechanism to contact that person (usually telephone) and inform them of the failure. I also provide usable feedback to senders for why I may have chosen to reject their message. And when it really matters, I also have a relay I can use for troublesome transports.