Follow this simple process for attaching mail to packages you want to transmit.
In some cases, mail contained in a package can provide evidence of project activities. If you want other organizations to have access to it, you can send it to them by attaching it to the transmittal. Anyone who can send packages can attach mail in this way.
The package’s recipient will find all the attached mails in read-only format within the package transmittal in the Mail Attachments section.
Recipients can also view attached mails from the Transmitted tab within the Package Mail. This area lists all Mail that was attached to that Package by the sender.
The Transmitted tab only shows mail you have received on a package transmittal. It does not display Mail that was attached and sent by your organization.