While it's not clear which domain of yours is being affected, earlier today the IP for principledprofit.com was listed on a blacklist. This could account for some of the delivery problems. Some of the returned emails may include additional information about the nature of the error, which may require manual intervention on your part. I see you have SPF records in place. As long as mail isn't being relayed through your SMTP servers through a compromised account, there's not much else you can do. The next step would seem to be more aggressive filtering on inbound messages. If you haven't already, consider an audit of your sites with a tool like WordFence. MailPoet - a popular and powerful plugin - has had some severe security issues that may have lead to your site becoming the source of the spam. In the past weeks, I've had customers compromised by phishing scams and weak passwords - both resulting in large volume of spam which was luckily caught promptly. Neither were related to WordPress but were PHP scripts installed to blast spam for as long as possible. Best of luck, - Jeff On 8/7/2014 9:32 AM, Shel Horowitz, Ethical/Green Marketing Expert wrote: > ** Be sure to fill out the survey/skills inventory in the member's area. > ** If you did, we all thank you. > > > My assistant just called me to tell me that e-mail she sent me was > blocked as probable spam, to both two of my domain emails and my > gmail address. I have also noticed that in the last two weeks, a lot > of the email I send (especially BCC) is being blocked for the same > reason--to four particular recipients. > > At the same time, I get nondelivery messages on my server from some > Russian spammer pretending to be me. > > Of course, the flow of inbound actual junk continues unabated. :-( > > Should we just go back to mailing letters, or are there workable solutions?