The line between helpfulness and spying often rests on the volunteer's sense of agency. You cross that line when your data usage shifts from supporting their mission to monitoring their behavior for internal control. To find the threshold, look at the source of the information. If you use data they explicitly shared—like their skills or availability—you are personalizing. If you are tracking things they didn't realize you could see, such as how long they linger on a specific webpage or their location via a mobile app, you are surveilling.
Watch for the "creepy factor" in your communications. When a volunteer receives an email that says, "Since you clicked that link about urban gardening three times last Tuesday, we thought you'd like this,” you have failed. They didn't ask for that level of granular tracking. Instead, try broader groupings. Instead of tracking individual clicks, use aggregated interests.
Transparency acts as your safeguard. If you cannot explain to a volunteer exactly why you are collecting a specific data point and how it helps them serve the cause better, do not collect it. When the data starts serving the manager's desire for oversight rather than the volunteer's ability to engage, you have gone too far.
