My office ISP is Verizon FIOS. My site is hosted on BlueHost (richgarifo.com) using the RoundCube webmail client.
A sender's support division is attempting to send me mail (email@example.com) but it is getting blocked. However, when I search the IP address in SpamCop the following comes up: "220.127.116.11 not listed in bl.spamcop.net". They can reply to an email I send them, but no message originating there is getting through. This .is a support site for a service I subscribe to and is very important.
Any insight on how to solve this "blocked-but-not-listed" problem is much appreciated.