If emails are sent out by using TLS 1.3 from a sender, what will happen on SMG 10.9.0 or earlier?
Article ID: 388269
Updated On:
Products
Issue/Introduction
If emails are sent out by using TLS 1.3 from a sender, will SMG 10.9.0 or earlier receives them? If not, will the sender receive a delivery failure notification? Will it be written in a SMG log or Message Audit logs?
Environment
SMG 10.7.4, 10.7.5, 10.8.x and 10.9.0
Resolution
Generally when TLS negotiation fails due to the either the sending server not being able to communicate at SMG's minimum TLS level or some other TLS negotiation failure, it's up to the sending MTA to decide how to proceed, e.g. tried TLS negotiation with lower TLS level, re-deliver in plain text next time, or etc.
Part of the TLS negotiation is negotiation of the maximum TLS version supported by client and server. If the SMTP sender can only do TLS 1.3, the TLS negotiation will fail because SMG 10.9.0 and earlier versions do not support TLS 1.3.
The TLS negotiation failure would be written in a SMG log, information level logs, as well as SMG Message Audit logs. However, it does not show why it failed and it will be written as a connection failure.
Additional Information
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