Is there such a service that will tell me the reputation of an email domain, i.e. whether mail originating at that domain would be likely to be treated as definitely spam or not? (I don't really care about "no reputation"; I want to know if a domain has known bad reputation.)
I feel like, if there was such a service, it would be pretty useful to use it to prevent account registrations on other services, from users whose email addresses have domains with bad reputations. After all, they'd very likely just be registering with the intent of using the service to send or post spam in some way.
Possibly interesting... but these are rules about outgoing SMTP servers (MSAs), yes? How much of a relation does the outgoing SMTP server for a domain have to the canonical set of receiving SMTP servers (MTAs) for the domain held in the domain's DNS MX record? These can certainly be one and the same server; but it's not a requirement. So how often are they in practice? Especially for people actively trying to evade these sorts of RBLs?
I feel like, if there was such a service, it would be pretty useful to use it to prevent account registrations on other services, from users whose email addresses have domains with bad reputations. After all, they'd very likely just be registering with the intent of using the service to send or post spam in some way.