There is an official version (for Android) here:
Why does the Dropbox Android app request access to my contacts?
The Android app uses your contacts to provide features that make it
easier for you to use Dropbox, including sharing with friends without
having to remember their contact info. For example, when you share
files and photos, Dropbox can suggest names and email addresses from
your address book as you type them.
Does Dropbox collect or save my contacts?
With your permission, Dropbox will sync information from your contacts
for your use.
Does Dropbox share my contacts with others?
We don’t share your contacts unless you request that we do so. If you
choose to share files with someone or invite a person to Dropbox, we
send an email on your behalf to that contact.
Can I use Dropbox without giving access to my contacts?
Starting with Android Marshmallow, users can grant optional
permissions when using an app instead of when installing an app. For
all users, Dropbox will only sync your contacts if you give us
permission to do so.
Why are contacts from a different device or app appearing in my Dropbox?
With your permission, Dropbox syncs contacts from devices on which you
use Dropbox. This feature makes it easy to share and collaborate with
all of your contacts directly from Dropbox, whether they're from a
linked device or a third-party source (Facebook, Google, Twitter, or
To Remove third-party service contacts:
Dropbox stores contacts from each third-party service you've connected
to your Dropbox account (such as Gmail or Yahoo). This feature makes
it easy to share and collaborate with all of your contacts directly
Follow the steps below to remove third-party service contacts from
your Dropbox, but note that this action will disconnect all
- Sign in at dropbox.com.
- Click your name or avatar at the top of any page.
- Click Settings.
- Click Account, or click Personal if you have paired personal and work Dropbox accounts.
- Under Connected services, click Remove all services and imported contacts.
- Confirm this action in the pop-up window by clicking Remove all.