E-Mail errors after update


I just updated my server edition to v

I was testing everything after update.

Went test e-mail and it failed and below error appeared.

I made no change to e-mail settings from previous version which had worked fine.

An error occurred while attempting to establish an SSL or TLS connection. This usually means that the SSL certificate presented by the server is not trusted by the system for one or more of the following reasons: 1. The server is using a self-signed certificate which cannot be verified. 2. The local system is missing a Root or Intermediate certificate needed to verify the server’s certificate. 3. A Certificate Authority CRL server for one or more of the certificates in the chain is temporarily unavailable. 4. The certificate presented by the server is expired or invalid. 5. The set of SSL/TLS protocols supported by the client and server do not match. See https://github.com/jstedfast/MailKit/blob/master/FAQ.md#ssl-handshake-exception for possible solutions.

Any ideas would be appreciated.

When did you upgrade last time before? I’m trying to pinpoint which change could have caused this.

Good morning,

I would have upgraded from version 23.7.13, in July.

I was out office for past few weeks, so I only upgraded yesterday when I was back in office.

Thanks for your help.

Did you try to re-enter and save the SMTP information (servers, port, username and password)?


Yes I did, no luck

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any luck yet? iam also struggling

when locally installed anti-virus software replaces the certificate in order to scan web traffic for viruses.

Switch your antivirus off, i did disable avast and now its working

I am having this identical issue. I updated about 2-4 days ago from approx 09/26/2023 is when I last updated it.
Also it is showing a slightly different error for me. Here is what it say when I hit test email settings.
I have verified all the settings to be correct.
Also it was working before the update.

Please update again to at least v23.8.23.997. Lots of issues with SMTP seem resolved with this version.

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I just updated to version and the same problem is persisting.

I tried to change my e-mail Server etc and same issues.

Yes I have the same issue as before. It is not fixed for me.
FYI I am using Win 11 and version


I have just updated Manager Server to Version

I adjusted my e-mail settings to use an old Microsoft Live Account and it worked.

There must be an issue with certain types of SSL Certs or who issues them.

Anyway my system is back fully working again, thanks for your help.