Shared Inboxes = Shared Risk
How addresses like “info@” and “accounts@” can quietly weaken your security
As an MSP owner, I come across this problem nearly every week.
A company will say, “We don’t have many users, just a few shared inboxes.”
Info@. Accounts@. HR@. Support@. It seems simple at first.
But in reality, shared inboxes are one of the biggest unmonitored security gaps for small and medium businesses. (Shojaifar & Fricker, 2020)This isn’t because shared inboxes are bad, but because no one is usually responsible for them.
Why Shared Inboxes Are a Security Blind Spot
Shared mailboxes were made to help people work together, not to keep things secure.
Still, many small businesses treat them just like regular user accounts. Here are some common problems:
- Multiple people know the same password
- MFA is skipped “because it’s inconvenient”
- No one monitors sign-ins
- No audit trail of who did what
- Departed staff still have access through Outlook or mobile devices (Only half of SMB leaders are confident that ex-employees can’t access the company’s digital assets, 2022)
For attackers, this situation is a big opportunity. (Junior et al., 2023)No human owner.
Low visibility.
High trust.
How Attackers Abuse Shared Mailboxes
When attackers gain access to a shared inbox, they don’t rush. They watch.
They learn how invoices are sent.
They study reply patterns.
They wait for the perfect moment. Common attacks we see:
- Invoice redirection from Accounts@
- Vendor impersonation using Info@
- Internal phishing sent from a trusted mailbox
- Silent forwarding rules to monitor conversations
- Password resets triggered using shared email access (Business Email Compromise | Prevention, Mitigation and Response, 2024)
Since several people use the mailbox, suspicious activity is often ignored with the thought, “Oh, maybe someone else did that.” (The Major Security Risks of Having a Shared Email, 2023)
The Compliance and Accountability Problem
Shared inboxes also make it hard to hold anyone accountable. (Technologies, 2026)When something goes wrong, the questions are painful:
- Who accessed the mailbox?
- Who clicked the link?
- Who approved the payment?
- Who changed the rule?
If everyone has access, then no one is truly accountable. For businesses in regulated industries or finance, this is a serious risk on its own. (Sayeed et al., 2024)
What We Recommend as an MSP (And Why)
We don’t ban shared mailboxes, but we make sure they are properly secured. Here’s what actually works:
- No direct sign-in to shared mailboxes
- Access only via delegated permissions
- MFA enforced on every user who can access it
- Conditional Access restrictions (location, device, risk)
- Audit logs reviewed regularly
- Mailbox activity alerts enabled
- Ownership clearly defined
And most importantly:
Shared inboxes should not be used as a shortcut to get around licensing or security controls.
The Real Business Risk Isn’t the Inbox
The biggest risk is actually trust. When a shared mailbox is compromised, customers don’t blame “IT.”
They blame you. Your brand.
Your credibility.
Your cash flow. Most small businesses don’t notice the damage until money is lost or their reputation is already hurt. (The Financial Impact of Cybersecurity Breaches on SMBs, 2023)
Final Thought from the MSP Side
Shared inboxes aren’t a technical problem.
They’re a governance problem. If your business relies on shared mailboxes, ask yourself one simple question:
Who is accountable for this inbox?
If you don’t have a clear answer, then your risk is already clear.
Jaspreet Singh — Author at MSPinsights.ca | Founder & CEO, Accelerate IT Services Inc.
References
Shojaifar, A. & Fricker, S. A. (2020). SMEs' Confidentiality Concerns for Security Information Sharing. arXiv preprint arXiv:2007.06308. https://doi.org/10.1007/978-3-030-57404-8_22
(October 9, 2022). Only half of SMB leaders are confident that ex-employees can’t access the company’s digital assets. Kaspersky. https://www.kaspersky.com/about/press-releases/only-half-of-smb-leaders-are-confident-that-ex-employees-cant-access-the-companys-digital-assets
Junior, C. R., Becker, I. & Johnson, S. (2023). Unaware, Unfunded and Uneducated: A Systematic Review of SME Cybersecurity. arXiv preprint arXiv:2309.17186. https://doi.org/10.48550/arXiv.2309.17186
(2024). Business Email Compromise | Prevention, Mitigation and Response. Palo Alto Networks. https://www.paloaltonetworks.com/cyberpedia/what-is-business-email-compromise-bec-incident-response
(2023). The Major Security Risks of Having a Shared Email. GreOnix. https://www.greonix.com/the-major-security-risks-of-having-a-shared-email/
Technologies, O. o. (2026). Why Avoid Shared Accounts?. University of Tennessee. https://oit.utk.edu/security/learning-library/article-archive/avoiding-shared-accounts/
Sayeed, S. A., Rahman, M. M., Alam, S. & Kshetri, N. (2024). FSCsec: Collaboration in Financial Sector Cybersecurity -- Exploring the Impact of Resource Sharing on IT Security. arXiv preprint arXiv:2410.15194. https://doi.org/10.48550/arXiv.2410.15194
(2023). The Financial Impact of Cybersecurity Breaches on SMBs. GXA. https://gxait.com/business-technology/the-financial-impact-of-cybersecurity-breaches-on-smbs/