I’m getting tons of messages with this “Rejected by spam filter” error. Is this my mail server’s spam filter (I use ProtonMail) or is this Cloudflare? I was under the impression that Cloudflare just does a straight passthrough without inspecting anything. Prior to moving my MX to Cloudflare, the MX was pointed to ProtonMail and I was receiving these same messages (in the spam folder). Yes, they 100% are spam, but I just want to understand what Cloudflare is doing upstream.
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Seems like CF is using UCEPROTECTL3 blacklist and this is a mess. Only owners of the ASN can request a removal or you pay an annual subscription. Even parts of the ip range from CF is marked as higth risk.
host route3.mx.cloudflare.net[162.159.205.23] said: 554 XX.XX.XX.XX found on one or more DNSBLs (uceprotectip3). Refer to Postmaster · Cloudflare Email Routing docs for more information.(in reply to RCPT TO command)
I just discovered the same problem with email forwarding thanks to a client. I don’t know how many mails I have lost so far.
I forward some email adresses from a domain name I own to my Gmail account and most of them seems blocked by Gmail considering they are spam while they are legitimate.
Unknown error: permanent error (550):
5.7.1 [2405:8100:c000:1::14:1f1 19] Our system has detected that this
5.7.1 message is likely suspicious due to the very low reputation of the
5.7.1 sending domain. To best protect our users from spam, the message has
5.7.1 been blocked. Please visit
5.7.1 https://support.google.com/mail/answer/188131 for more information.
sb8-20020a\xxxxxxxxxxxsi5207883ejc.637 - gsmtp
Someone knows how to fix this?
You may want to start a new topic as this one is over two years old and likely unrelated to whatever your are encountering.