When you get an e-mail with *.eml attachments save the eml attachment to your Computers temp directory; best if you create a separate directory in /tmp like /tmp/juno
To unpack the eml file you need to install the mpack package.
sudo apt-get update && sudo apt-get install mpack
Go to the location you saved the eml file.
cd /tmp/juno munpack file.eml
Files in the eml get unpacked and are locate in /tmp/juno