Trying to email our supplier, we are receiving the message below:

Reporting-MTA: dns; googlemail.com
Received-From-MTA: dns; [email protected]
Arrival-Date: Mon, 16 Mar 2020 03:46:25 -0700 (PDT)
X-Original-Message-ID: <[email protected]>

Final-Recipient: rfc822; [email protected]
Action: failed
Status: 7.5.0
Remote-MTA: dns; alt1.us.email.fireeyecloud.com. (3.93.93.51, the server for
the domain mx.us.email.fireeyecloud.com.)
Diagnostic-Code: smtp; TLS Negotiation failed, certificate invalid: SSL [Leaf certificate is expired]
Last-Attempt-Date: Mon, 16 Mar 2020 03:46:26 -0700 (PDT)

Does this mean that they only accept valid TLS and their domain certificate has expired?

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