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Error: "The following addresses had permanent fatal errors" from mailer-daemon@...
Open the mailer-daemon message to find the reason of the delivery failure.
If the message was sent to several recipients, you should usually find the address that failed in the following lines :
----- The following addresses had permanent fatal errors -----
(reason: 550 Host unknown)
----- Transcript of session follows -----
550 5.1.2 <email@example.com>...
Host unknown (Name server: abc.xxx: host not found)
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