It’s become increasingly critical in the last few years, and many email service providers and third parties are now offering email collaboration tools or added features. It’s certainly the case with Microsoft’s shared mailbox on Office 365.
In this article, you will learn everything you need to know about Office 365 shared mailboxes: what it means, how to use it, its benefits & how to connect it to your Missive account for added features.
What is an Office 365 shared mailbox?
Simply put, shared mailboxes are email inboxes that multiple teammates or colleagues can access.
Typically, these inboxes are most often used for your sales@, info@, and support@ email addresses within a business. These email addresses are common across most industries and typically require more than one person to work out of.
Office 365 shared mailbox is Microsoft’s version of this delegation tool and is available for all users who have an Outlook mailbox email address. The shared account needs to be created by an admin account that can then edit permissions through the account settings by inviting collaborators. When adding collaborators, you can choose between the following mailbox permissions: full access, send as or send on behalf.
Everyone who has access to a Microsoft Outlook account can create, share, or be invited to a shared mailbox and can read, reply to, forward emails, and write new emails.
It’s worth noting that the Office 365 shared mailbox can be accessed from the same login information, but invites will be sent through individual user email accounts. Shared mailboxes are free, and included in Microsoft's Exchange Online, and any user can have complete access to an unlimited number of shared mailboxes, but each shared inbox has a data storage limit of 50GB.
You can’t log into a shared mailbox directly using Outlook or Outlook Web App (OWA): you must first be granted permissions to the shared mailbox. Additionally, if you have automapping enabled in your business (by default), the shared mailbox will automatically appear in your user’s Outlook app after you restart Outlook.
Finally, if you use Outlook for iOS or Outlook for Android, you can add or access a shared mailbox on the Outlook Mobile app.
Why use an Office 365 shared mailbox?
Sharing emails from a shared mailbox address has many advantages, like:
Better productivity
One of the most significant benefits of a shared mailbox is its productivity among team members. Everyone who has access to this shared email account has a complete overview of the incoming emails and can monitor threads without forwarding them. You also have access to shared mailbox rules.
Better transparency
With a shared mailbox, everyone can see the whole email message chain and threads, allowing clear transparency and no more chasing for information from coworkers while reducing the risk of missing an email or replying twice.
Pro Tip: For even better organization, you can use Outlook's folders to organize emails sentor associate a specific project with a folder, so you can quickly see which email belongs to which person.
Better responsiveness
Is someone out of the office for the day? Other team members can still respond to messages for better responsiveness. This can help your customer service as any team member can respond to inquiries faster.
By following shared mailbox best practices you can take benefit from these advantages. But is Microsoft Office 365 shared mailbox the perfect fit for you? Keep on reading, and you will find out.
How to create a shared mailbox with Office 365
Creating a shared mailbox is relatively simple if you already have an Office 365 Outlook account. Here are a few steps:
- Sign in with a global admin account or Exchange admin center.
- In the Office 365 admin center, go to the Teams & Groups > Shared mailboxes page.
- On the Shared mailboxes page, select + Add a shared mailbox. Enter a name for the shared mailbox.
- Select Save.
- Under Next steps, select Add members to this mailbox. Members are the people who will be able to view the incoming mail to this shared mailbox and the outgoing replies. It can be a group of people or individual users.
- Select the + Add members button. Put a checkmark next to the people you want to use this shared mailbox, and then select Save.
- There you go! You can now use your shared mailbox.
Are Office 365 shared mailboxes enough?
Although shared mailboxes are a good idea in almost every department, Office 365’s version offers significant limitations, such as the lack of integrations with other apps and functionalities, but most importantly, flawed collaboration:
- You can’t coordinate with teammates on who should take care of an email.
- You can’t chat with teammates in the context of an email thread.
- You can’t create tasks related to the specific email.
Because an Office 365 shared mailbox, at its core, is just a sharing mechanism. It lacks the collaboration tools needed to improve your team productivity.
But you are lucky, you found us! We, at Missive, provide powerful team collaboration features on top of any Office 365 accounts (regular accounts or shared mailboxes).
Once everything is set up, you and your team will have access to the history of your shared account but under a perfectly crafted collaborative interface.
Missive is a shared mailbox on steroids!
Collaborative writing
Get feedback from your teammates in real-time, as they can highlight text, make changes or leave comments in the draft composer’s comment column.
Chat around emails
Chatting around emails is a crucial feature for true team collaboration. It allows team members to communicate and solve the customer's issues right in the context of their emails.
Share labels
Create team labels (known as folders in Outlook) to get more organized in your email management. Easily create them right from a conversation or from the Labels tab in your settings. You can even customize the color or add a unique icon.
Assign emails and create tasks
With Missive, you can assign emails or conversations to a single user or a group of people. When it is assigned to you, it will appear at the top of your Inbox. The conversation will also appear in Assigned to me and your Inbox.
You can also create tasks within emails, or have them be standalone — all visible through a global task view.
Share canned responses
With saving time in mind, Missive allows you to create templates or canned responses that you can share with a team. Canned responses are predetermined responses to common questions. This means that you and your team have a ready-made answer for each question, and you don't have to come up with a new response each time.
Inserting a response in a draft is really easy with the search option.
When dealing with common questions, having a canned response ready to go can be beneficial. You can quickly and easily give the recipient the information they need without having to come up with something from scratch each time. This can be helpful in many situations, such as customer service or sales.
Integrate with your tools
You can connect integrations like Asana, Hubspot, Trello, and Shopify. This allows you to manage your workflows and tasks in one place. Having all of your tools in one place makes it easier to stay organized and get work done.
Security and compliance
Email can contain lots of sensitive information, which is why Missive holds itself to similar enterprise-level security standards as Outlook. Including achieving SOC 2 Type II compliance, a widely recognized auditing standard for service providers that ensures the operational effectiveness of our security controls over time.
And more!
You will also be able to customize your user interface by choosing between three themes, assigning tasks and conversations, handling events from a calendar within the app, etc.
Frequently asked questions
What is an Office 365 shared mailbox?
An Office 365 shared mailbox is a mailbox that multiple users can access without a separate license. Common addresses like info@, support@, or hr@ are typically set up as shared mailboxes so multiple team members can send and receive from them. They're managed through the Microsoft 365 admin center and don't require their own user license, as long as members access them through their own licensed accounts.
Are Office 365 shared mailboxes free?
Yes, with caveats. Shared mailboxes themselves don't require a separate license, but every user accessing one needs their own Microsoft 365 license. The shared mailbox itself is limited to 50 GB of storage and can't be used to log in directly. For teams already paying for Microsoft 365, shared mailboxes are effectively free as part of the existing subscription.
How many users can access an Office 365 shared mailbox?
Microsoft doesn't impose a hard limit on user permissions, but practical performance starts to degrade with more than ~25 simultaneous users. The mailbox is also capped at 50 GB total storage by default (expandable to 100 GB with an Exchange Online Plan 2 license assigned to the mailbox). For teams that hit either ceiling, dedicated shared-inbox software typically scales further.
What are the limitations of Office 365 shared mailboxes?
Office 365 shared mailboxes work for basic shared access but lack the collaboration features modern teams expect.
- No assignment. Anyone can reply to anything, with no clear ownership of who's handling which conversation.
- No collision detection. Two team members can reply to the same email at the same time without warning.
- No internal notes inside conversations. Teammates can't discuss an email without forwarding it or switching to a different tool.
- Limited automation. Server-side rules exist but are basic compared to dedicated shared-inbox tools.
- No analytics or reporting. No native way to see response times, volume by team member, or trends.
- Storage caps. 50 GB by default, which fills up quickly for high-volume support addresses.
What's the difference between an Office 365 shared mailbox and a tool like Missive?
An Office 365 shared mailbox is a Microsoft feature that gives multiple people access to the same inbox. Missive is a dedicated shared-inbox application that connects to your Microsoft 365 account (or Gmail, or IMAP) and adds the collaboration layer that's missing natively: assignment, threaded internal chat inside emails, real-time collaborative drafts, rules-based automation, and multichannel support.
Office 365 shared mailboxes are free if you're already paying for Microsoft 365. Missive starts at $14/user/month for paid plans, or free for teams up to 3 users.
When should you upgrade from Office 365 shared mailboxes to dedicated software?
The trigger points teams describe most often:
- You've sent the same reply twice because two people answered the same email.
- You can't tell who's working on what without asking.
- Internal discussion about emails is happening in Slack, in DMs, or in CC chains, instead of with the email itself.
- You're hitting the 50 GB storage cap or noticing performance issues.
- You want to know response times, volume per agent, or trending topics, and Outlook doesn't tell you.
If any of those resonate, dedicated shared-inbox software (Missive, Front, Help Scout, Hiver) is worth evaluating.
Can you assign emails in an Office 365 shared mailbox?
Not natively. Office 365 shared mailboxes don't have an assignment feature; anyone with permission can reply to anything. Teams typically work around this by adding categories or moving emails to subfolders, but those are workarounds, not assignment. Dedicated tools like Missive add real assignment with status (open, closed, snoozed), notifications, and reporting.
Do Office 365 shared mailboxes show who's replying?
No. There's no native collision detection, so two people can start replying to the same email simultaneously without either knowing. Some teams notice this only after sending duplicate or contradictory responses to a customer. Tools like Missive show real-time presence (who has the email open, who's drafting a reply) so the team can avoid stepping on each other.
How do you create an Office 365 shared mailbox?
Through the Microsoft 365 admin center: go to Teams & Groups, then Shared Mailboxes, click Add a Shared Mailbox, name it, give it an email address, and assign team members who need access. Members will see the shared mailbox alongside their own inbox in Outlook automatically. Setup takes a few minutes, but the result is basic shared access without any of the collaboration features dedicated tools provide.
