Can't send mail without SSL / TLS

[definitio]

Enable SSL / TLS is unchecked. Mail server doesn't use SSL / TLS.
Log:

May 17 18:41:18 media jellyfin[117]: [18:41:18] [ERR] Error sending email
May 17 18:41:18 media jellyfin[117]: MailKit.Security.SslHandshakeException: An error occurred while attempting to establish an SSL or TLS connection.
May 17 18:41:18 media jellyfin[117]: The server's SSL certificate could not be validated for the following reasons:
May 17 18:41:18 media jellyfin[117]: • The server certificate has the following errors:
May 17 18:41:18 media jellyfin[117]:   • self signed certificate
May 17 18:41:18 media jellyfin[117]:  ---> System.Security.Authentication.AuthenticationException: The remote certificate was rejected by the provided RemoteCertificateValidationCallback.
May 17 18:41:18 media jellyfin[117]:    at System.Net.Security.SslStream.SendAuthResetSignal(ProtocolToken message, ExceptionDispatchInfo exception)
May 17 18:41:18 media jellyfin[117]:    at System.Net.Security.SslStream.ForceAuthenticationAsync[TIOAdapter](TIOAdapter adapter, Boolean receiveFirst, Byte[] reAuthenticationData, Boolean isApm)
May 17 18:41:18 media jellyfin[117]:    at MailKit.Net.Smtp.SmtpClient.ConnectAsync(String host, Int32 port, SecureSocketOptions options, Boolean doAsync, CancellationToken cancellationToken)
May 17 18:41:18 media jellyfin[117]:    --- End of inner exception stack trace ---
May 17 18:41:18 media jellyfin[117]:    at MailKit.Net.Smtp.SmtpClient.ConnectAsync(String host, Int32 port, SecureSocketOptions options, Boolean doAsync, CancellationToken cancellationToken)
May 17 18:41:18 media jellyfin[117]:    at MediaBrowser.Plugins.SmtpNotifications.Notifier.SendNotification(UserNotification request, CancellationToken cancellationToken)
May 17 18:41:18 media jellyfin[117]: [18:41:18] [WRN] Slow HTTP Response from http://jellyfin.home/Notification/SMTP/Test/5cc7bde5a02e47b2a3f8029c8916c899 to 10.10.1.50 in 0:00:00.8615494 with Status Code 204

[quielb]

I also have this issue. It looks like there are two things that are causing this.

The first is how the option is stored in config. I don't know C# well enough to know if the option is read back in as a string or a boolean. Either way that value need to be "evaluated".

In MediaBrowser.Plugins.SmtpNotifications/Notifier.cs on line 52 client.ConnectAsync is called passing in options.SSL which is read from the config file. That value is either or boolean or a string, but neither type is correct. The function requires an enum of type SecureSocketOptions from MailKit.Security

I think there needs to be a line of code before the connect is called to evaluate the option and set the enum correctly:
(Assuming bool type from config)

SecureSocketOptions use-SSL = options.SSL ? SecureSocketOptions.Auto : SecureSocketOptions.None;

Then replace options.SSL with use-SSL in client.ConnectAsync

As a work around I have disabled TLS on my internal MAIL relay. Since it's internal it's not really needed.