Shared mailboxes are one of Microsoft 365’s most useful features. They allow multiple employees to access and manage a common email address—such as info@yourcompany.com, support@yourcompany.com, or sales@yourcompany.com—without everyone sharing the same username and password.
When configured correctly, shared mailboxes improve collaboration while maintaining accountability and security.
However, if they’re not set up properly, they can become a security risk and create unnecessary headaches for your business.
Let’s look at some best practices to help keep your Microsoft 365 shared mailboxes secure.
What Is a Shared Mailbox?
A shared mailbox is designed to let multiple authorized users:
- Read incoming emails
- Send emails from a common address
- Manage a shared calendar
- Collaborate without sharing passwords
Unlike a traditional user account, employees sign in with their own Microsoft 365 credentials, then access the shared mailbox through Outlook.
That distinction is important—and much more secure.
Why Shared Mailboxes Are Better Than Shared Accounts
Some businesses still create a single Microsoft 365 user account for everyone in a department to share.
For example:
- reception@company.com
- accounting@company.com
- shipping@company.com
Everyone uses the same password.
While it seems convenient, it creates several problems:
- No accountability
- Shared passwords
- Difficult employee offboarding
- Weak Multi-Factor Authentication (MFA)
- Poor audit trails
A shared mailbox solves these problems by allowing every employee to authenticate with their own account.
Best Practice #1: Give Every Employee Their Own Microsoft 365 Account
Every employee should have:
- Their own username
- Their own password
- Their own MFA enrollment
Then simply grant them access to the shared mailbox.
This allows Microsoft 365 to record exactly who accessed the mailbox and what actions they performed.
Best Practice #2: Enable Multi-Factor Authentication
Although users don’t log directly into a shared mailbox, they do log into their personal Microsoft 365 accounts.
That means every employee with access should have MFA enabled.
If someone’s credentials are stolen, MFA provides another layer of protection before attackers can reach the shared mailbox.
Best Practice #3: Only Give Access to Employees Who Need It
Not everyone needs access to every mailbox.
Review permissions regularly and follow the principle of least privilege:
Only give employees the access they need to perform their jobs.
The fewer people with access, the smaller your security risk.
Best Practice #4: Remove Access Immediately When Employees Leave
One of the biggest advantages of shared mailboxes is how easy they are to manage.
When an employee leaves:
- Disable their Microsoft 365 account
- Remove mailbox permissions
- Verify they no longer have access
There’s no need to change passwords for the entire department because no passwords were ever shared.
Best Practice #5: Review Permissions Regularly
Businesses change.
Employees change roles.
Departments grow.
Unfortunately, mailbox permissions often stay the same for years.
Schedule regular reviews to answer questions like:
- Who still has access?
- Does everyone still need it?
- Are former employees completely removed?
Regular permission reviews reduce unnecessary exposure.
Best Practice #6: Monitor for Suspicious Activity
Shared mailboxes can still be targeted if an employee’s account is compromised.
Watch for:
- Logins from unusual locations
- Unexpected forwarding rules
- Suspicious emails being sent
- Unauthorized permission changes
Microsoft 365 provides logging and reporting that can help identify unusual behavior before it becomes a major problem.
Best Practice #7: Avoid Using Shared Mailboxes for Everything
Shared mailboxes work well for collaboration, but they aren’t the right solution for every situation.
Consider alternatives when appropriate:
- Microsoft Teams for internal collaboration
- Shared document libraries for files
- Distribution lists for announcements
- Security groups for permission management
Using the right Microsoft 365 tool helps improve both productivity and security.
Common Mistakes We See
Here are a few issues we frequently encounter:
❌ Sharing one Microsoft 365 login among multiple employees
❌ Not enabling MFA
❌ Former employees still having mailbox access
❌ Too many employees with unnecessary permissions
❌ No one reviewing mailbox permissions over time
These small oversights can create significant security risks.
The Bottom Line
Shared mailboxes are one of Microsoft 365’s best collaboration features—but only when they’re configured properly.
By giving each employee their own Microsoft 365 account, enforcing Multi-Factor Authentication, limiting access, and regularly reviewing permissions, your business can improve both productivity and security.
It’s a simple change that can dramatically reduce risk while making mailbox management much easier.
Secure Your Microsoft 365 Environment with SandStorm IT
At SandStorm IT, we help businesses across the Mid-South get the most out of Microsoft 365 while keeping their environments secure.
Whether you need help configuring shared mailboxes, implementing Multi-Factor Authentication, reviewing permissions, or improving your overall Microsoft 365 security, our team is here to help.
We believe technology should make your business more productive—not more vulnerable.
👉 Contact SandStorm IT today at 901-475-0275 to schedule a Microsoft 365 security review and ensure your business is following industry best practices.