UPDATE: If you have upgraded to DSM 5.0, click on Share files one time using private link Synology DSM5.0
If you want share files with somebody without adding them as users, Synology has a feature to do this.
Here is how you do it:
3. Select the file you want to share and click on Share file links:
4. Click on Validity period:
5. Click on Customize Validity Period, that is how long you want the option to download the link last. For example, if you want the link to be available for download one week, click on A week. For other options click on Customize…
6. If you want the link to be password protected, click on Password:
7. Click on Enable password protection and add password for your link, click ok:
8. How do you notify your recipiant that they have a link available to download their files? Either you send them the link manually and the password or you click on the Mail link:
9. They will receive an email or the link and will be sent to the following window:
10. The only thing they have to do is to click on the link, write the password and the file will download automatically:
And it is done, Enjoy!