SYMPTOMS

When sending to the mail server via SMTP and TLS, the server responds with an error saying TLS is not available due to temporary reason. It happens when users try to send email, and possibly even for inbound email. The following is an example bounce message that occurred when a Gmail account tried sending to a MailEnable hosted address with the issue:

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Message will be retried for 2 more day(s)

Technical details of temporary failure:

Google tried to deliver your message, but it was rejected by the recipient domain. We recommend contacting the other email provider for further information about the cause of this error. The error that the other server returned was:

454 454 TLS not available due to temporary reason (state 9).

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CAUSE

• Cause 1: SMTP inbound TLS has been enabled but no SSL certificate (or no valid certificate) has been selected to be used.
• Cause 2: The Windows account that the SMTP service is running under (usually IME_SYSTEM or IME_ADMIN) does not have permissions to access the selected SSL certificate or the Microsoft Windows "SystemCertificates" registry branch. 

RESOLUTION

• Cause 1: In the administration program, expand the Servers branch and right click on the "localhost" icon. Select Properties from the popup menu, which wil present an options window. Select the SSL tab and select a valid certificate. For further details please review the MailEnable documentation under the "Localhost - Secure Sockets Layer (SSL) encryption" chapter for information and steps on how to configure an SSL certificate to be used within MailEnable.
• Cause 2: Please review the following article to ensure permission settings have set for the SSL certificate and the "SystemCertificates" registry branch: https://www.mailenable.com/kb/Content/Article.asp?ID=me020479

If the problem still occurs, check the SMTP Debug log for the error, as it will indicate the exact problem.