Web.de / SMTP error code 550
smtp;550 <example@example.com>: Bad DNS PTR resource record
Emails from your email server were rejected because the PTR Resource Record of your IP address does not follow their guidelines. Possible reasons for this can be: The PTR-RR states that the IP address was dynamically allocated or the PTR-RR is a generic standard entry of your provider. Please allocate an independent and fully qualified domain name to your email server.
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