qwest

Lumen Technologies, aka CenturyLink, absorbed Embarq, combined with Qwest, which acquired USWest (if you’ve really been around a while) and is a telecommunications provider come together from many parts, with bits of them descended all the way from Mountain Bell, Pacific Northwest Bell and Northwestern Bell, the latter being the predecessor company that ran the copper wires that eventually delivered DSL internet service to my Minneapolis apartment starting near the turn of the millennium. Fast forward to today, and they continue to provide consumer internet access in various locales across the USA, and that includes hosting consumer email services for those users across a number of domains. Those domains include:digisys.netcswnet.commebtel.netcenturylink.netq.comembarqmail.comgrics.netcenturytel.netqwest.netcoastalnow.netgulftel.comThe MX for these domains points at mx.centurylink.net, but if you connect on port 25 and read the SMTP banner, you’ll see “cloudfilter.net” which is actually Cloudmark. Thus, if you’re having spam-related deliverability troubles at CenturyLink, you’ve probably got a Cloudmark