# Managing Access to Confidential Documents: A Case Study of an Email Security Tool  
[PERSON]  
1 Department of Software Engineering, University of Jeddah, Makkah 23445, Saudi Arabia; [EMAIL_ADDRESS]  
[PERSON]  
2 School of Information Technology, Illinois State University, Normal, IL 61761, USA  
Our study seeks to understand user perceptions of an email security tool and how they use it to manage access control to their confidential information. The existing literature on email encryption tools mostly focuses on studying usability for performing encryption. They did not investigate access control (i.e., how users would use the tools' security features to manage access control to various types of sensitive content sent via email). We chose Virtru [12] over other secure email tools (such as Private Webmail (Pwm), ProtonMail, PGP (Mailvelope), Gmail Confidential Mode (GCM), and Tutanota) due to its usability and user preference [10; 13], as well as fine-grained security features such as automatic key management, integration with users' existing Gmail accounts, allowing non-Virtru recipients to read encrypted email without Virtru being installed, and having built-in access controls that can help Gmail users control their emails after they are sent. Our study targets first-time Virtru users, since we were interested in first impressions and the likelihood of adopting this tool for sharing and receiving sensitive content via email. Additionally, we focus on the most common sensitive forms and documents users send via email, as shown by one [PERSON] et al. [10]. Therefore, we investigate user perceptions of Virtru and how they use its security features to manage access control to three types of confidential information, namely medical, tax, and employee personal information, if sent via email. More specifically, our research questions are the following:  
* RQ1: What are users' first impressions when receiving an end-to-end encrypted email using an email security tool?
* RQ2: How comfortable are users with sharing various types of confidential information (medical, tax, and employee) using an email security tool?
* RQ3: How do users use an email security tool's additional features to manage access control to their confidential information?  
To answer these research questions, we conducted an interview-based user study on 19 participants. Our results showed that the participants' first impression upon receiving an encrypted email was that, due to the tool's interface, it looked suspicious, especially when received from an unknown person. However, after they were informed about the benefits of using the tool, they were comfortable sharing medical, tax, and employee information forms via the tool. Regarding managing access control to the three types of confidential email information, the expiration time and disabling forwarding were the most useful features for the participants for preventing unauthorized and continued access, and the only reason for not using them was to prevent unforeseen accessibility issues for the recipient. While the participants did not understand how the persistent protection feature worked, many still chose to use it, assuming it provided some extra layer of protection to prevent unauthorized access to all three types of confidential information. Watermarking was the least useful feature for the participants, irrespective of the type of confidential information in the email, as many were unsure of its usage. Our participants were more concerned about data leaks from recipients' devices (for instance, if their email account were to be compromised) if they set a longer expiration date (such as a year). Our findings provide practical implications that could help users share confidential information via end-to-end encryption tools.