Rolf,
I there is a feature on dropbox to where you can share any one file with a person. All you have to do is log in at the dropbox website. Find the file you need to email and click down arrow-like button in the files row. There will be an option to “Get Shareable Link” Click it and email the link you get to whomever needs the file. If you don’t see that option visit this link to enable the option: https://www.dropbox.com/enable_shmodel
Thanks,
Brandon