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TBird Daily 60.0a1 (2018-02-26 64-bit) claims SMTP Server Cert is invalid

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  • Last reply by WoofGrrrr

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Thunderbird Daily 60.0a1 (2018-02-26 64-bit) claims that my SMTP Server's certificate is invalid.

This is the most-recent release of DAILY, installed yesterday. It prevents me from sending outgoing email.

I get a dialog with the title "Add Security Exception".

The dialog says that the site with location smtp.1and1.com:587 "attempts to identify itself with invalid information. " It also says "Unknown Identity" and "The certificate is not trusted because it hasn't been verified as issued by a trusted authority using a secure signature."

When I switch to the most-recent release of Thunderbird - 52.6.0 (32-bit), there is no such problem.

Thunderbird Daily 60.0a1 (2018-02-26 64-bit) claims that my SMTP Server's certificate is invalid. This is the most-recent release of DAILY, installed yesterday. It prevents me from sending outgoing email. I get a dialog with the title "Add Security Exception". The dialog says that the site with location smtp.1and1.com:587 "attempts to identify itself with invalid information. " It also says "Unknown Identity" and "The certificate is not trusted because it hasn't been verified as issued by a trusted authority using a secure signature." When I switch to the most-recent release of Thunderbird - 52.6.0 (32-bit), there is no such problem.

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Who does issue the certificate?

Periodically certification authorities are removed, such as the removal of Startcom SSL certificates. Knowing exactly which certifying Authority the certificate is issued by would help.

Second, is your email connection secured by SSL/TLS. If so have you disabled mail scanning in your anti virus product of choice. None can scan email on such connection, unless your insert the anti virus are a certifying authority. Personally I do not trust any anti virus vendor that much.

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This continues to be a problem with today's release of DAILY 60.0a1 (2018-02-27 64-bit)


SSL Certificate Hierarchy: thawte Primary Root CA thawte SSL CA - G2 smtp.1and1.com

Serial Number: 5D:E6:0C:18:CE:F1:E6:9C:CE:5A:DD:58:3C:F4:5B:D4


Connection security for this SMTP server is set to STARTTLS. I don't have mail scanning with my anti virus.


Again, this is a problem only with DAILY, not with the production release of Thunderbird