Self-signed certificate rejected

Self-signed certificate rejected

Anthony Abell Beginner Posts: 3 Points: 2 Rating: 2236 Authority: 2236 Joined: 02 March 2020	#1 0 03 September 2025 05:31:13 I download email from my own server. I use TLS connections, but with TB 11.4.3, the handshake fails because the certificate is self-signed. I have added it to the certificate store (address book), but it is still rejected. I can now only download mail by clicking OK in the dialog that pops up. But I should not have to do that. What is the workaround?

Miloš Radovanović Guru Posts: 568 Points: 1022 Rating: 8645 Authority: 8640 Joined: 30 September 2021	#2 0 03 September 2025 12:32:54 I'm not sure it will work in your case, but try Options -> S/MIME and TLS... -> Microsoft CryptoAPI

Anthony Abell Beginner Posts: 3 Points: 2 Rating: 2236 Authority: 2236 Joined: 02 March 2020	#3 11849.3777 03 September 2025 17:45:49 Problem solved. This was a new machine I just built, and the motherboard driver package included a particular Norton Antivirus version, which it installed. Norton was trapping the self-signed certificate, inserting itself into the TLS handshake. I uninstalled the Norton AV. No more TLS issues.

Miloš Radovanović Guru Posts: 568 Points: 1022 Rating: 8645 Authority: 8640 Joined: 30 September 2021	#4 0 03 September 2025 18:48:51 Great, thanks for the feedback, this is good to know. I was just writing the other day on another thread about avoiding old bloated AV software. Case in point!

Edward Reid Master Posts: 63 Points: 113 Rating: 1137 Authority: 1132 Joined: 03 August 2015	#5 0 05 September 2025 22:37:15 AV software vendors must pay a lot of money to get their bloatware bundled, since modern Windows systems don't need it. Apparently the advertising is working, as I constantly hear people worrying about what AV they should have.

Miloš Radovanović Guru Posts: 568 Points: 1022 Rating: 8645 Authority: 8640 Joined: 30 September 2021	#6 0 06 September 2025 08:57:28 Exactly. On all computers I have, MS Defender and common sense have been doing the job for years now.