Administrator: It's now possible to sort the lists under Undelivered Messages and Live log again.
WebAdmin: A robots.txt has been added to prevent search engines from trying to index WebAdmin.
Core: The stability of the thread pool has been improved.
Core: The message deliverer performance has been improved slightly.
Core: The return-path header is now added when the message is put into the user account, rather than when the message is received from the sending SMTP client / server. The reason is that according to the SMTP spec, SMTP servers should add the header when making the final delivery.