We have run our servers with a decoy, our MX records have been like this for 10+ years:
mx0.example.com mx1.example.com mx2.example.com mx1 & mx2 are real servers. mx0 is nothing, it points to an IP address that is controlled by us but there is no server. The concept being that some spammers attempt that server, get nothing and don't bother trying any other server. This has been fine for a decade. In the last few weeks we are finding that SOME (but not all) of Yahoo's outbound servers are not dealing with this correctly. They don't try the other servers in the MX record list. They continue to try delivery for a few hours to mx0 and then return the following error to the sender: *Sorry, we were unable to deliver your message to the following address.* *<u...@example.com <u...@example.com>>:* *Unable to deliver message after multiple retries, giving up.* We have confirmed this with a few domains that we host so far, even setup a brand new domain and server to to testing with to verify that our suspicion was true, Yahoo is not correctly dropping down to lower priority servers anymore. Has anyone else seen this? Rob
