Cloud Email Gateway
Protection adds a layer of protection by validating the
reverse DNS (rDNS) records for inbound email messages.
With the reverse DNS validation feature, an administrator can configure the following:
-
Validation settings: whether to reject an email message when the corresponding PTR record is missing or invalid
-
Block list: a list of PTR domains for message blocking
During the SMTP connection setup stage, Cloud Email Gateway
Protection uses the
email sending IP address to perform rDNS lookup. If the query result matches the criteria
in any
rDNS validation settings or the PTR domain block list, Cloud Email Gateway
Protection rejects the email message before the message body is
sent over.
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NoteIf the IP address sending an email message matches the Approved IP address list of
IP
reputation, the email message bypasses revere DNS validation.
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