In early versions of CA Service Desk Manager (CA SDM), such as CA SDM 12.6, both mail.jar and activation.jar appear to have been packaged in the product. Some guidance had been provided in some CA documentation. Specifically, both technical document TEC598391 and solution document RI61075 refer to those two files. The two files are actually JDK add-ons. For example, the file named "mail.jar" is part of some early versions of JavaMail.
In a CA SDM 14.1.03 environment, "mail.jar" is not included in the files under the NX_TOMCAT_INSTALL_DIR.
For example, the NX.env file under the base CA SDM installation directory (referred to as $NX_ROOT) indicates the location of Tomcat, but the lib directory at that location does not include "mail.jar", as shown in the screenshot below:
Although you may find a copy of mail.jar and activation.jar under $NX_ROOT\java\lib, neither the JavaMail package nor the named files are mentioned in the Supportability Matrix and so they are unsupported.
However, it is possible that you could successfully use the files with your implementation. The files can be copied to the $NX_ROOT\CA\SC\tomcat\7.0.23\lib folder for that purpose.
JavaMail is an open source project. For JavaMail 1.5.6, mail.jar is not included; instead, javax.mail.jar is included.
You may download JavaMail 1.5.6 (or possibly a later version of JavaMail) from the primary official source web page - please see the Additional Information section for a suggested link.
From within the downloaded package, you could copy the file named "javax.mail.jar" into the $NX_ROOT\CA\SC\tomcat\7.0.23\lib directory. It should then be possible to extend the use of attaching files to CA SDM tickets via the intended method.
On the date that this technical document was created (2017-April-21), the primary official source web page for obtaining the JavaMail add-on is: https://java.net/projects/javamail/pages/Home