NoClassDefFoundError: javax/activation/DataSource

In case you use maven you can add manually

<dependency>
    <groupId>javax.activation</groupId>
    <artifactId>activation</artifactId>
    <version>1.1.1</version>
</dependency>

I added activation.jar to buildpath and the problem is solved.

So i used 2 jars java-mail-ima.** .jar, activation.jar (for further referebces).