I copied a project from one folder to another in the file System. Then I opened it through eclipse and tried to run the programs. I got the following error message when the program starts by creating an object:
java.lang.SecurityException: class "javax.mail.Message"'s signer information does not match signer information of other classes in the same package.
I have a mail.jar on the project's buildpath and at the end of the program an email will be sent. But the exception is thrown at a line that is still far from sending emails.