You can use the file list variable in the email message body without the file attribute (name). That will give you a list of the files that include the folder path.
${retfiles}
If you do not want the path information, then you can create a temporary print file.
You would need to do a For Each loop thru the file list.
Using the PRINT task, write the file name to a temporary file: ${retfiles:name}${system.lineFeed}
Then using that temporary file, Add a File to the message body.
for example:
<forEachLoop itemsVariable="${retfiles}" currentItemVariable="CurrentItem">
<print file="${system.job.workspace}TempFile.txt" version="1.0">
<![CDATA[${CurrentItem:name}${system.lineFeed}]]>
</print>
</forEachLoop>
<sendEmail resourceId="HelpSystem" toList="
[email protected]" keyLocation="KeyVault" version="2.0">
<from address="
[email protected]" keyLocation="KeyVault" />
<subject>
<![CDATA[test]]>
</subject>
<message file="${system.job.workspace}TempFile.txt" />
</sendEmail>