Question

I need to send an email using Javamail and TLS (not STARTTLS, but a dedicated smtp port just for SSL/TLS!). I only managed to find examples for gmail, that however use STARTTLS. Can somebody please post an example for normal SSL/TLS? Thank you very much!

Answer 1

The official examples for JavaMail with Gmail use SMTPS (i.e. SMTP over SSL/TLS on a dedicated port) and not STARTTLS. Essentially, the properties using JavaMail should be mail.smtps.* instead of mail.smtp.*.

If you want to force a specific version of SSL/TLS, for example TLSv1.0, you’ll need to create your own SSLSocketFactory, possibly wrapping the default SSLSocketFactory (or anything else you would have customised), but you need to call sslSocket.setEnabledProtocols(new String[] { "TLSv1" }) before returning the socket.

You’ll need to pass that SSLSocketFactory either as an instance via the mail.smtps.ssl.socketFactory configuration property, or as a fully qualified class name via mail.smtps.ssl.socketFactory.class (in this case, you class must implement a static method called getDefault).

To prevent MITM attacks, you also need to make the client verify the server host name: you need to set mail.smtps.ssl.checkserveridentity to true, since it seems to be false by default.