On 11Jul24, Cody Millard via mailop apparently wrote: > What is "A RR" ?
Sounds like they're talking about DNS A RRs (Address records). Circa 1986 the DNS community introduced the MX RR with a view to transitioning away from how a mail client would look up an address RR directly for a target domain and connect to that. Nearly 1/2 a century later, it's still the case that most mail clients will look for address RRs in the absence of an MX. > > A RR for incoming messages. do you know why they design this? for better > > anti-abuse control? It could be just laziness. As for anti-abuse benefits, I recently re-activated a 1/4 century old dormant domain to see how much spam was still sent to it. It was quite a lot. But, I did note that when that domain only advertised A/AAAA RRs the volume was slightly lower, by about 10-15%. So avoiding MX RRs might provide some marginal anti-spam benefit, but I guess it's also possible that more recent mail clients or mail client libraries may not fall back to address RRs in the absence of an MX and thus such a domain might miss genuine email. Mark. _______________________________________________ mailop mailing list [email protected] https://list.mailop.org/listinfo/mailop
