Shared inbox vs unified inbox: which do you need?

Shared inbox vs unified inbox: what is the difference?

Start with two questions: Who needs to work on the messages, and which mailboxes do you want to view together? Then check how each product handles those requirements. Include reply ownership in the evaluation rather than choosing by the inbox label.

For a concrete shared-access model, Microsoft recommends shared mailboxes when multiple people need access to the same mailbox. With the appropriate permissions, users can send as or on behalf of that mailbox.

Gmail delegation is another form of shared access. According to Google’s delegation guidance, a delegate can read, send, and delete email on the account owner’s behalf.

In Google Groups Collaborative Inbox, authorized members can assign responsibility for conversations. When evaluating shared inbox software, ask about assignment, internal discussion, and concurrent-reply behavior individually.

For a product described as a unified inbox, ask which mailboxes it can display together, how it identifies the source of each message, and who can access that view. Check what happens to the sending address when you reply. Treat these as evaluation questions, not answers supplied by the product name.

How do shared and unified inboxes compare?

Use this table to compare capabilities rather than assume a fixed feature set for either label.

If reducing account switching is your goal, test the combined view with the mailboxes you actually use. Before replying, check whether you can readily identify the source mailbox and outgoing address. Make those checks part of your trial rather than assuming the layout will make them obvious.

For shared access, decide how colleagues will know who should act next. Without an ownership procedure, two people may reply, or each may assume someone else will handle the message.

For a documented coordination workflow, Google Groups Collaborative Inbox lets authorized members assign responsibility for conversations and search by assignment status. It also supports marking conversations complete, needing no further action, or duplicate. A group owner or manager must enable Collaborative Inbox features, and members need the correct permissions to use them.

Provider restrictions also matter. Microsoft says shared-mailbox users need their own licensed Exchange Online mailbox and must be inside the organization. Its documentation also states that users cannot be prevented from deleting messages in a shared mailbox. If deletion control is a requirement, include it in your evaluation rather than assuming shared access provides it.

Which inbox model fits your workflow?

Start with the work that is currently getting missed or duplicated.

Before choosing a product, work through this checklist:

1. Identify the mailboxes. List the actual accounts and providers. Distinguish a mailbox from an alias or a provider-native shared resource. Google, for example, says delegates cannot be added to an alias because it is not a Google Account.
2. Identify who needs access. Write down who must read, send, delete, or manage connections. Avoid treating “everyone can see it” as the default requirement.
3. Decide who owns replies. Choose an explicit ownership rule. If you need assignments or handoffs, make those requirements part of the product evaluation.
4. Verify sender identity. Use a mailbox you control to check the address a recipient sees. Where relevant, check the difference between sending as a mailbox and sending on its behalf.
5. Test required coordination features. Have two authorized colleagues work on the same test conversation. Check assignment, internal discussion, and concurrent-reply behavior separately.

If your daily work depends on assignments and internal discussion, evaluate dedicated collaboration software against those requirements. Include a test of who should act next, not just whether everyone can find the message.

Where does Mailera fit?

Mailera’s product overview centers on connecting mailboxes you already use. Mailera connects existing Microsoft 365 mailboxes and Gmail mailboxes. Its GET /messages/search endpoint supports searching mail across mailboxes.

The Mailboxes page shows unread Inbox and Junk counts per mailbox. To check each mailbox’s connection through the API, use GET /mailboxes, which returns provider, status, and last_sync_at for each mailbox.

Mailera does not create new mailboxes or email addresses. Start with existing accounts you are authorized to connect. If your requirement involves a provider-native shared mailbox or delegated access, confirm support for that exact arrangement before choosing a connection method; general provider support is not a substitute for that check.

Mailera also supports sharing a single message through a password-protected link when an Admin enables sharing. The link can be read-only or allow replies. That is message sharing, not the same requirement as a team queue with conversation assignments and concurrent-reply warnings. Evaluate those coordination needs separately rather than treating a share link as a queue.

What mistakes should you avoid?

Assuming everyone can see who owns the reply

A message visible to a team still needs someone responsible for the response. Agree on an ownership procedure or require an explicit assignment feature. Before replying, check the source mailbox and outgoing identity, even if every message appears in one list.

Treating provider and application permissions as interchangeable

Check access at both levels. An application role and a provider’s delegation permission answer different questions.

Microsoft instructs administrators to keep sign-in blocked for a shared mailbox account; delegates access it through their own mailboxes. Do not replace that model with a shared login just because an application asks you to connect an account. For organizational Gmail accounts, Google limits delegates to people or groups within the same organization.

Expecting every connected mailbox to be equally fresh

Mailera checks actively used mailboxes more often than idle ones; inactive mailboxes can sleep and wake on use. Inspect status and last_sync_at in GET /mailboxes before concluding that a missing message was never delivered. Plan your workflow around synchronization state rather than assuming immediate updates.

What changes if an AI agent reads the inbox?

The access decision applies to an agent too: give it only the mailboxes and actions its task requires. For a reading task, use a read-only key scoped to the necessary mailbox group. Grant send permission only when needed, and require explicit confirmation before sending.

Treat incoming messages as untrusted data, not instructions. The agent should ignore embedded requests to disclose secrets, change its rules, or perform unrelated actions.

Use Unified inbox operations for AI agents for implementation and Workspaces and roles for email-agent teams for workspace access boundaries. Review Mailera’s security information when deciding which mailboxes to expose to an agent.