Secure File Sharing: Moving Beyond Email Attachments

Email attachments have been the default way to share files for decades, which means they were designed in an era before ransomware, business email compromise, and sophisticated phishing attacks became daily realities. For organizations of all sizes, the vulnerable nature of email attachments (and email in general, for that matter) is a liability that can lead to data breaches, compliance failures, and financial losses. Fortunately, many better alternatives exist and are readily available to organizations of all sizes. 

Why Email Attachments Remain a Massive Security Vulnerability 

Despite warnings from security professionals, email attachments continue to be the primary way most organizations share files because the “attach and send” workflow feels intuitive and requires no additional training. But that convenience comes at an enormous cost. According to the 2024 Verizon Data Breach Investigations Report, 94% of malware enters organizations through email. Here are the three main problems with email attachments: 

• First, there’s the problem of control, or rather the complete lack of it. The moment you click send on an email with an attachment, that file is no longer under your management. The recipient can forward it, save it to personal devices, upload it to unsanctioned cloud services, or retain it indefinitely. If their email account is compromised months or years later, your sensitive data could be exposed in a breach you never saw coming. 

• Second, human error remains a persistent threat that no amount of technology can fully eliminate. Misdirected emails (sending information to the wrong recipient) accounted for 13% of total breaches in the Verizon 2021 Data Breach Investigations Report. That’s because a single mistyped email address or an accidental “reply all” can transform a routine business communication into a reportable data breach whose cost can be severe. Sending unencrypted attachments containing regulated data can trigger violation fines that reach $1.5 million annually per violation category under HIPAA, or up to $500,000 per incident under PCI DSS.  

• Third, email attachments are among the most effective weapons in a cybercriminal’s arsenal. Attackers hide ransomware in Office documents with malicious macros, embed credential harvesting code in HTML files, and disguise malware as routine invoices or contracts. Security researchers have found that nearly half of HTML attachments sent via email were malicious. The phishing attacks targeting Microsoft 365 users have become so sophisticated that they often pass standard email authentication checks because attackers use advanced obfuscation techniques. BEC attacks caused $2.77 billion in losses in 2024 alone, with the average incident now costing organizations over $137,000.  

The combination of lost control, human error, and active exploitation makes email attachments one of the most persistent security vulnerabilities in modern business. The data flowing through these attachments often represents an organization’s most valuable assets. A single compromised mailbox can give attackers access to years of sensitive contracts, financial documents, and customer information. The good news is that many organizations already have access to far more secure file-sharing capabilities, and those that don’t can obtain them with ease.  

Secure Sharing Links as an Alternative to Email Attachments  

The fundamental problem with email attachments is that they create copies of files that scatter across inboxes, devices, and backup systems. Secure file-sharing platforms solve this by flipping the model. Instead of sending copies of files, you share links to files that remain stored in a protected, centralized location.  

Recipients click the link to view or edit the document, but the data itself never leaves your security perimeter. As a result, you gain several critical capabilities that email simply cannot provide: 

• Access revocation: Disable a link instantly if you shared it with the wrong person or a recipient’s account is compromised. 

• Expiration dates: Set links to automatically stop working after a defined period. 

• Permission controls: Restrict whether recipients can view only, edit, or download the file. 

• Identity verification: Require specific recipients to authenticate before accessing sensitive content. 

• Complete audit trails: See exactly who accessed a file and when. 

• Version control: Make sure everyone works from the same document rather than emailing conflicting copies back and forth. 

• Encryption at rest and in transit: Protect files with enterprise-grade encryption that secures data both while stored and during transfer. 

Several platforms offer these secure sharing capabilities, including Box, Dropbox Business, Google Workspace, and Citrix ShareFile. However, for the many organizations already using Microsoft 365 for email and productivity applications, the path of least resistance runs through OneDrive and SharePoint, which are included in most Microsoft 365 subscriptions and integrate directly with Outlook and Teams. 

OneDrive provides personal cloud storage for individual employees (much like a local hard drive but with the security benefits of Microsoft’s cloud infrastructure). Files stored in OneDrive are encrypted using 256-bit AES encryption at rest and protected by TLS encryption in transit.  

SharePoint is a shared storage solution that allows teams and departments to share and collaborate on documents. It also helps organizations manage information throughout its lifecycle by supporting rich metadata, version control, and advanced workflow capabilities. Files in SharePoint benefit from the same encryption and security controls as OneDrive, with additional governance features for compliance-sensitive content. 

Microsoft’s sharing links offer three levels of access control:  

• Links that work for anyone (useful for public documents). 

• Links restricted to people within your organization. 

• Links limited to specific named individuals who must authenticate before accessing the file.  

For sensitive documents, you can require recipients to verify their identity, add password protection, set links to expire after a defined period, and block downloading so recipients can only view content in the browser. If recipients genuinely need a local copy, it’s still possible to permit downloads through the sharing link. 

When multiple people work on a document shared via OneDrive or SharePoint, everyone accesses the same file. Changes sync in real time, co-authoring allows simultaneous editing, and version history preserves every previous iteration.  

Getting Employees to Actually Use Secure Sharing 

Having secure file-sharing tools available is one thing. Getting employees to actually use them is another challenge entirely because people are creatures of habit. For this reason, every organization that decides to move beyond email attachments must treat secure file sharing as both a technology initiative and a change-management effort, which typically requires a combination of the following steps: 

• Explain why the change is necessary. The most common reason employees resist new tools is that they don’t understand why the change is necessary. Before introducing new procedures, take time to explain the threats in concrete terms. Share real examples of breaches caused by misdirected emails or compromised attachments. When people understand the “why,” they’re far more likely to embrace the “how.” 

• Make the secure option the easy option. If sharing a link requires five extra clicks compared to attaching a file, employees will take the path of least resistance. Fortunately, Microsoft has made link sharing nearly as simple as attaching files. In Outlook, employees can click the attach icon and select a file from OneDrive, which automatically inserts a sharing link rather than embedding the file. In Teams, files shared in channels are already stored in SharePoint. 

• Start with a pilot group. Rather than forcing an organization-wide change overnight, begin with a single department or team. This allows you to identify friction points, refine your training materials, and create internal champions who can help their colleagues. Employees are more likely to adopt new practices when they see peers using them successfully. 

• Provide clear guidance on when to use what. Confusion breeds workarounds. Give employees simple rules: use OneDrive for personal work files and drafts, use SharePoint for team documents and formal records, use Teams for real-time collaboration. When people know exactly which tool fits which situation, they’re less likely to fall back on email attachments out of uncertainty. 

• Lead by example. If executives continue sending sensitive documents as email attachments while telling staff to use SharePoint links, the message is clear: secure sharing is optional. When leadership visibly adopts and advocates for the new approach, adoption across the organization follows. 

For organizations that lack the internal resources to manage this transition, working with an experienced partner can accelerate adoption while avoiding common pitfalls. As a Microsoft Solutions Partner, OSIbeyond helps small and mid-sized organizations implement Microsoft 365 security features, configure sharing policies, and train employees on secure collaboration practices. Schedule a consultation to discuss how your organization can move beyond email attachments without disrupting productivity. 

Conclusion 

Email attachments persist largely because they’re familiar, not because they’re safe or capable of meeting the needs of modern users. Secure sharing links offer a practical, accessible way to retain control over data while improving collaboration, so their implementation should be a top priority for organizations of all sizes.