I\'d like to send mail without bothering with the SMTP-Server which is used for delivery.
So JavaMail API doesn\'t work for me because I have to specify a SMTP server to
Don't.
Sending email is much more complex than it seems. Email servers excel at (or should excel at) reliable delivery.
Set up a separate email server if you need to- that will be essentially the same as implementing one in Java (I doubt you will find libraries for this task- they would be essentially complete mail servers), but much more simpler.