“MLX”

My client is using iCloud Mail with his custom domain and he communicated with many govt organizations which seem to all be using Barracuda Email Protection for their spam prevention. I have properly configured his SPF, DKIM & DMARC DNS records however his emails were still being rejected. (Email header below) I contacted Barracuda support with the email header and they replied saying that the emails were rejected becuase Apple Mail has missing PTR records. I have sent dozens of emails for testing and looking at all their headers I can see (ms-asmtp-me-k8s.p00.prod.me.com [17.57.154.37]) which does not have a PTR record. ----FULL EMAIL HEADER WITH 3RD PARTY DOMAINS REMOVED----- : host d329469a.ess.barracudanetworks.com[209.222.82.255] said: 550 permanent failure for one or more recipients (recipient_email_address:blocked) (in reply to end of DATA command) Reporting-MTA: dns; p00-icloudmta-asmtp-us-west-3a-100-percent-10.p00-icloudmta-asmtp-vip.icloud-mail-production.svc.kube.us-west-3a.k8s.cloud.apple.com