In my popular series about idiotic blocklists, this time a particularly brilliant stupid idea from SpamCop.net. They now list a server if it routes emails to downstream systems and then routes error messages back out. Short, our company scenario: our customers are served via our central mail server, but usually have their own mail systems (Exchange or Linux systems). For this reason, we have to accept emails for some of the customers, regardless of what the local part is - we have no control over who is all configured in the Exchange. Furthermore, these systems are dynamically connected, which is why a live check is also out of the question. Of course, the mail systems generate bounces for these incorrect addresses - and of course, bounces also occur on virus spam. However, our customers have a legitimate interest in these bounces, as only then do their partners find out about typos in addresses.
Spamcop, on the other hand, now believes that bounces should not be forwarded, that one must absolutely check at the SMTP level at the very front. Or one must route bounces via a separate IP, which is then blocked by Spamcop, which would be no problem (huh? but the legitimate bounces do not reach the recipient if they are behind someone who uses this incompetently administered list).
Technically, this means that Spamcop arrogates to itself the decision that a mail server may not forward bounces if it has accepted a mail. According to Spamcop's opinion, bounces may only pass as a rejection at the SMTP level, the classic bounce mails are in their opinion a reason to enter someone in a blocklist. They even go so far as to say that any form of autoresponders is forbidden and leads to an entry in their blocklist.
A blocklist, by the way, whose alleged goal is to reject spam. Which is clearly refuted here once again - SpamCop has just as much of its own agenda as any other blocklist operator, and as usual (see SORBS with the entries as a hacked server, for example, if FTP is running on an unusual port) it shines through incompetence.
By the way, we have activated Sender-Verify on our mail servers, which means that only emails get through whose technical sender is certified as valid by their own MX. Therefore, we only bounce on addresses that are at least considered valid by their own MX. These are no "misdirected bounces" on invalid addresses, unless the MX of these addresses lies (then it is their own problem).
Mail operators who use such blocklists to reject mail server connections are acting irresponsibly. One of them is at Microsoft ...