Installing a Mail Client
For this solution you'll need a throwaway Gmail account, as you are going to specify your Gmail password in a configuration file.
Start by installing the tools you'll be using to send emails:
sudo apt-get install ssmtp
sudo apt-get install mailutils
sudo apt-get install mpack
Next, run:
sudo nano /etc/ssmtp/ssmtp.conf
and ensure that file contains the following configuration parameters, making sure that your Gmail account credentials are in place:
root=postmaster
mailhub=smtp.gmail.com:587
hostname=raspberrypi
AuthUser=yourgmailusername@gmail.com
AuthPass=yourgmailpassword
FromLineOverride=YES
UseSTARTTLS=YES
Finally send a test email with an attachment from the target_dir directory:
mpack -s "Test Email" [target_dir/filename] [recipientEmailAddress]
If this mail arrives you are good to go to the next step.