How to send signed emails from java?

Question

What APIs/Libraries do you recommend for sending signed emails from Java code? What are the requirements on our company's SMTP-Server to make it transport these signed mails, if any?

We already hava a PKI infrastructure running, so certificates are no issue here.

Answer 1

The BouncyCastle S/MIME library is easy to use and compatible with common mail clients that support secure mail.

BouncyCastle also offers PGP-style email support, but this usually requires recipients to install a plug-in or find other support for signature verification.

In both cases, the signed messages are just MIME messages like any other email. No special treatment is required at the server.

Answer 2

Here:

http://www.example-code.com/java/smtp_sendSigned.asp