I have observed the issue shared by you and request you to please first try using Aspose.Email for .NET 19.11 on your end. If there is still an issue then please share the working sample project along with test account credentials reproducing the issue. Please share the source information so that we may try investigating issue on our end.
I have observed the information shared by you. An issue with ID EMAILJAVA-34630 has been created in our issue tracking system to further investigate and resolve the issue. This thread has been linked with the issue so that you may be notified once the issue will be fixed.
I have verified from our issue tracking system and like to share that you need to use new implementation of SocketsLayer to connect server using Aspose.Email for Java 19.12.
//enable TLS1.2 support with Sockets Layer version 2
EmailClient.setSocketsLayerVersion2(true);
//open connection
SmtpClient client = new SmtpClient("host.com", 587, "user", "pass");
client.noop();