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Email is not delivered after disabling SSL to protect from POODLE vulnerability

Knowledge Article Number 000206241
Description Disabling SSLv2 and SSLv3 in a receiving mail system to protect from the POODLE vulnerability stops the reception of email from some sending Domains.

The email logs on Salesforce show this transient failure (mail event T) with the delivery status notification "451 4.7.5 [internal] TLS negotiation failed."
Resolution Please confirm that TLS is remains enabled in the email systems after SSL is disabled.  If TLS is not available without SSL, then please reach out to the MTA Vendor to see if any patches are available to allow TLS without SSL.

Please see this Information Security Stack Exchange post for more information about this issue:


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