Regular Visitor
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6 Messages
Undelivered Mail Returned to Sender
Starting some time yesterday morning, emails that are forwarded by rules from iCloud mail have been returned to sender. I get an email from iCloud with subject "Undelivered Mail Returned to Sender" with a lot of unreadable text starting with
<REDACTED@comcast.net>: host mx1.mxge.comcast.net[96.102.18.146] said: 530
5.1.0 <ALSO-REDACTED@icloud.com> sender rejected (in reply to MAIL FROM
command)
This just started yesterday morning. Forwarding was successful until then.
It seems to have been corrected a few minutes ago.
What happened, and will it happen again?
XfinityChristy
Official Employee
•
2.6K Messages
12 hours ago
What Happened?
Spam Protection: When iCloud forwards mail, it can look like "spoofing" to Comcast. If the original sender has a low reputation, Comcast may temporarily block the incoming iCloud server to prevent spam.
IP Greylisting: Comcast’s automated systems likely flagged a specific iCloud IP address. Since service has resumed, the block was likely cleared automatically once the system verified the traffic was legitimate.
Will it happen again?
It is possible, as automated filters are constantly updating. To protect your mail:
Keep Copies: Ensure your iCloud rule is set to "Forward and Keep a Copy" so no mail is lost if a block recurs.
Whitelist: Add your iCloud address to your Comcast/Xfinity address book.
If this persists, contact Comcast Security Assurance at https://internetsecurity.xfinity.com/help/report-abuse/ to request a manual whitelist.
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