When Outlook blocks a file, upload it to OneDrive or your organization’s approved SharePoint location and send a sharing link instead. This is Microsoft’s recommended approach. Set access for the intended recipients, check whether they can edit or download the file, and remove access when sharing is no longer needed. Work or school accounts may have additional restrictions, so follow your organization’s policy.
Why Outlook blocks some attachments
Outlook blocks certain file types as a security measure because attachments can carry computer viruses. Microsoft lists examples such as .bat, .exe, .vbs, and .js, but those examples are not the full list. The exact behavior can depend on the Outlook product and organizational settings. See Microsoft’s blocked file types guidance.
As an Amazon Associate I earn from qualifying purchases.
Microsoft’s recommended alternative is to send a OneDrive link rather than attach the blocked file. A secure network location such as SharePoint may also be appropriate when it is approved by your organization. Microsoft explains this in its guidance on blocked attachments in Outlook.
Send a link with access limited to the right people
- Upload the file. Put it in OneDrive or, for work or school, the SharePoint location your organization permits for this kind of file.
- Create a sharing link. Choose the link setting that matches the sensitivity of the file. Where available, select Specific people and invite the intended recipients. Microsoft notes that an Anyone link can be forwarded, and anyone who receives it may be able to access the content. See Microsoft’s external and guest sharing guidance.
- Set recipients’ permissions. If people only need to read the file, remove editing permission. For supported view-only OneDrive for work or school links, you may also be able to select Block download; this option is not available for every account or configuration. Details are in Microsoft’s Block downloads guidance.
- Check access before sending. Confirm the recipients and permission settings in the sharing dialog. For sensitive material, verify that the recipients can open the link in the context they will use; account and administrator settings can affect access.
- Send the link, then close access when finished. When recipients no longer need the file, use Manage access to remove their access or stop sharing.
Which method should you use?
| Method | Access control and convenience | When it makes sense |
|---|---|---|
| OneDrive or SharePoint link | Supports permission management; recipients’ access depends on account, sharing settings, and organizational policy. | Best default, especially for work or school files when the service is approved. |
| ZIP archive | May change the attachment’s extension, but the enclosed file can still behave as before; it does not make that file safe. | Only a secondary workaround for a trusted recipient who understands the contents and where policy permits it. |
| Renamed extension | Can confuse recipients and may bypass an extension-based block; it does not change the file’s underlying behavior. | Generally prefer a controlled sharing link instead. If used, do so only with a trusted recipient who knows the actual file type. |
| Administrator-approved exception | An Exchange administrator may be able to allow selected attachment types; availability is a policy decision. | For legitimate recurring business needs, ask the organization’s IT administrator rather than changing security settings yourself. |
Microsoft documents ZIP compression and renaming as workarounds, not as security measures. Only open a file when you trust its source and know what it is. For more on opening and handling attachments, see Microsoft’s Outlook attachment guidance.
#1 Best Overall
- Certified to FIPS 197 - High-level information security standard approved by the U.S. Government
- Brute-Force Password Attack Protection - Data is automatically erased after 6 failed access attempts. The data and encryption key are securely destroyed and the crypto drive is reset
- Rugged Double-Layer Waterproof* Design - Protects the crypto drive against knocks, drops, break-in and submerging in water. The electronics are shielded by a hardended inner case. The rubberised silicone outer casing provides a final layer of protection
- Auto-lock - The crypto drive will automatically encrypt all data and lock when removed from a PC/Mac or when the screen saver or "computer lock" function is activated on the host PC/Mac
- Secure Entry - Data cannot be accessed without the correct high-strength alphanumeric 8-16 character password. A password hint option is available. The password hint cannot match the password
What to do if the recipient cannot open the link
A link is not guaranteed to work for every recipient. OneDrive or SharePoint restrictions, external-sharing rules, or permissions may prevent access. Work or school SharePoint sites can also restrict particular file types. Check the organization’s OneDrive and SharePoint restrictions. If the file or link is blocked, ask the sender or your organization’s administrator which approved location or transfer method to use.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What not to change
Do not treat renaming or zipping a file as protection against malware: these approaches alter how the file is packaged or identified, not what it does when opened. Avoid changing registry settings or lowering Outlook’s security controls to get one attachment through. Microsoft’s legacy guidance on potentially unsafe attachments warns that changing security settings can reduce protection. For a legitimate business exception, involve the administrator.
Quick Recap
Best Value
- FIPS 140-3 Level 3 (Pending) Certified Military-Grade Security
- OS/Device Independent
- XTS-AES Hardware Encryption
- Enforced Alphanumeric PIN
- Multi-PIN (Admin and User) Option
Rank #4
- FIPS 197 with XTS-AES 256-bit Encryption: Provides business-grade security with hardware-based encryption to protect your sensitive data
- Brute Force and BadUSB Attack Protection: Safeguards against unauthorized access attempts and malicious USB attacks with digitally-signed firmware
- Multi-Password Option with Complex/Passphrase modes: Offers flexible password configuration options to meet various security requirements and user preferences
- New Passphrase Mode: Enhanced security feature allowing users to create longer, more memorable password phrases for easier access without compromising protection
- Dual Read-Only (Write-Protect) Settings: Enables write protection functionality to prevent accidental data modification or deletion when needed
Rank #3
- Certified to FIPS 197 - U.S. Government Approved High Level Information Security Standard.
- Protection against brute force password attacks - Data is automatically erased after 6 unsuccessful access attempts. The data of the USB flash drive type c encryption with dual connectors is destroyed and the cryptographic drive is reset.
- Durable dual-layer waterproof design* — Protects the crypto reader from bumps, drops, run-in and immersion in water. The electronics are protected by a hardened internal case. Rubberized silicone outer case provides a final layer of protection.
- Auto-Lock —The cryptographic key automatically encrypts all data and locks when removed from a PC/Mac or when screen protection or "computer lock" is enabled.
- Secure Entry —Data on these flash drives cannot be accessed without the correct alphanumeric password of 8 to 16 characters. A password indication option is available for this flash drive. The hint cannot match the password.
Rank #2
- Certified to FIPS 197 - High-level information security standard approved by the U.S. Government
- Brute-Force Password Attack Protection - Data is automatically erased after 6 failed access attempts. The data and encryption key are securely destroyed and the crypto drive is reset
- Auto-lock - The crypto drive will automatically encrypt all data and lock when removed from a PC/Mac or when the screen saver or "computer lock" function is activated on the host PC/Mac
- Secure Entry - Data cannot be accessed without the correct high-strength alphanumeric 8-16 character password. A password hint option is available. The password hint cannot match the password
- SuperSpeed USB 3.0 - Transfer all your confidential files and folders faster than ever before. Works on both PC & Mac
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
Recommended Free Tools
