Google Groups Collaborative Inbox: capabilities and published limits

What Google publishes that a Collaborative Inbox does

Google's own documentation describes Collaborative Inbox as a mode any Google Group can be switched into: "Group owners and managers can make any of their groups a Collaborative Inbox, where group members can take and assign conversations and perform other collaboration tasks." (Source: support.google.com/a/users/answer/10375787, checked 2026-08-11.)

Members with the correct permissions can, in Google's own words:

• "Take a conversation they volunteer to respond to."
• "Assign responsibility for a conversation to another group member."
• "Mark a conversation as complete, duplicate, or no action needed."
• "Search for conversations according to resolution status or assignee."

(Source: support.google.com/a/users/answer/10375787, checked 2026-08-11.)

The permission model is split in two. Google states that taking, assigning, unassigning, and marking a conversation completed all require "Who can moderate metadata," while marking a conversation as duplicate or as no action needed requires "Who can moderate content." (Source: support.google.com/a/users/answer/10375787, checked 2026-08-11.)

A few related behaviors round out the feature: assigning a conversation sends "an automated email notification," and any text in the "Add a note to assignment email" field "appears directly in the body of that automated email"; marking a conversation as duplicate "locks the conversation so that you can't perform any actions on it"; a resolved conversation can be deleted, and if it is, it "disappear[s] permanently and you can't restore [it]"; and labels "let you categorize conversations across assignment and resolution status." (Source: support.google.com/a/users/answer/167430, checked 2026-08-11.)

What Google states you need before you can turn it on

Two prerequisites, both stated directly by Google. First, the service itself: "If Google Groups isn't available in your work or school account, ask your administrator to turn on Groups for Business." Second, a setting inside it: "To enable Collaborative Inbox features, you must turn on conversation history." Google does not list which Google Workspace editions include Collaborative Inbox on the pages checked — only this pair of prerequisites is stated. (Source: support.google.com/a/users/answer/10375787, checked 2026-08-11.)

The published limits

Google's Groups for Business limits page states these numbers directly, and frames them as a set: "The Google Groups for Business service has limits for message activity, group size, invitations, and membership. If you reach one of these limits, your activity is temporarily restricted. Restrictions typically last an hour but can last as long as 24 hours." Each figure below is quoted verbatim, with its own source and checked date.

• Forwarding and Cc limit for Collaborative Inbox groups — "Emails forwarded or Cc'd from Collaborative inboxes — 25 email addresses per message." This one is Collaborative-Inbox-specific; the rest apply to Groups for Business generally.
• Conversation history storage — "Total messages stored in conversation history — Maximum number of emails stored in conversation history if this feature is enabled, per group — 300 per 5 minutes."
• Inbound email per group — "Total inbound emails per group — Maximum number of emails a group can accept from all senders combined — 300 per 5 minutes."
• Individual message size — "Individual message size — Maximum total megabytes (MB) that can be sent — 25 MB."
• Emails per sender to one group — "Total emails per sender to any one specific group — 1,800 per hour."
• Group membership — "Total membership, per group — Maximum number of members a group can have — Unlimited."
• Group ownership — "Total group ownership — Maximum number of groups a user can be an owner of at any one time — 1,500 groups."
• Members added at once — "Total member additions at one time — Maximum number of internal and external members that can be added at one time using a web interface — 200 per session."

Google adds one more statement that matters for the two limits above: "Group invitation and size limits only apply to actions performed in the Google Groups UI, groups.google.com. Groups administrators can add more members to a group using the Admin console or the Google Workspace Admin SDK Directory API." (Source: support.google.com/a/answer/6099642, which redirects to knowledge.workspace.google.com/admin/groups/understand-groups-policies-and-limits, checked 2026-08-11.)

Google's own caveat

Google states this directly on the same page as the limits above: "These limits can change without notice to protect Google's infrastructure." Treat every number on this page as a snapshot checked on 2026-08-11, not a fixed ceiling, and check Google's current page before relying on any of them operationally.

Google's own upgrade path: Gmail delegation

Google names its own next step for teams that outgrow the Groups for Business numbers above: "For advanced collaboration, set up delegated accounts in Gmail, where you can share inboxes among 40–1,000 users." (Source: support.google.com/a/users/answer/10375787, checked 2026-08-11.) The figures behind that range, and the fine print around them, are their own published set:

• Concurrent access — "With typical use, 40 delegated users can access a Gmail account at the same time. Above-average use by one or more delegates might reduce this number."
• Automation reduces that number further — "Automated processes that frequently access Gmail might also reduce the number of delegates who can access an account at the same time. These processes include APIs or browser extensions that access Gmail frequently."
• Total delegates — "A single Gmail account supports up to 1,000 unique delegates. A group in Groups counts as one delegate toward the limit."
• Delegates added through the Gmail API — "Gmail limits the number of delegates for each user in a Google Workspace organization to a maximum of 25 delegates." (Source: developers.google.com/workspace/gmail/api/guides/delegate_settings, checked 2026-08-11.)

Google is explicit that delegation is a different access model, not a bigger version of the same one: "Delegation does not increase the limits for a Gmail account. Gmail accounts with delegated users have the standard Gmail account limits and policies." Delegation is also scoped to one organization — "Users can only delegate access to another user in the same organization, regardless of their domain or their organizational unit" — and delegates "can then read, send, and receive messages on behalf of the user," though "Autocomplete isn't available to delegated users when using the Gmail search bar in the delegated account." (Source: support.google.com/a/answer/7223765, checked 2026-08-11.)

Signals you are at a wall

Each of these pairs a published limit with the operational situation that reaches it. None of them is a statement that Collaborative Inbox cannot do something — Google's documentation describes what the feature does and states numeric limits; it does not enumerate what it lacks.

• Bulk forwarding to stakeholders outside the group. The published limit is 25 addresses per message on emails forwarded or Cc'd from a Collaborative Inbox. A team that routinely loops in more than 25 external addresses on one forwarded thread is past that specific, Collaborative-Inbox-specific number.
• A burst of inbound mail or history writes. The published limits are 300 emails per 5 minutes for both total inbound mail to the group and for conversation-history storage. A spike — an incident, a mass mailing landing in the group, a bulk import — that clears either figure inside a five-minute window is a documented restriction risk, with Google's own note that the resulting restriction "typically last[s] an hour but can last as long as 24 hours."
• One very large message or attachment. The published individual-message-size limit is 25 MB. A message over that size is past the stated ceiling regardless of anything else about the group.
• One address sending heavily into a single group. The published limit is 1,800 emails per hour from any one sender to any one specific group. An automated system or a single very active correspondent pushing past that rate into one group has reached the stated number.
• Adding a large batch of members through the Groups UI. The published limit is 200 member additions per session when done through groups.google.com. Google's own answer for this one is not a wall: it states an admin can add more members through the Admin console or the Admin SDK Directory API instead, since the UI limit is stated to apply only to "actions performed in the Google Groups UI."

What is not a documented wall, because Google does not publish one: total group membership. Google's own words are "Total membership, per group — Unlimited," with no Collaborative-Inbox-specific ceiling or recommended size anywhere in the pages checked.

Where an agent changes the picture

Everything above is about Google's own published limits on the Collaborative Inbox feature itself — none of it is about adding an AI agent to the workflow. If a team's actual question is how an agent should be allowed to take, assign, or reply inside a shared inbox once it's part of the queue, that is a separate, permission-and-review question rather than a Groups for Business capacity question, and it holds whether the inbox is a Collaborative Inbox, a Gmail-delegated account, or something else entirely. DuoInbox is built as that governance layer for a Google Workspace shared inbox — triggers, permission levels, a review queue, and an audit log around Hermes as the initial agent.

To be plain about it: if the published capability set above covers what your team does, and none of the published numbers is close, staying on the native Collaborative Inbox is the right answer and nothing here is an argument to leave it. DuoInbox's own pricing, packaging, and availability are not yet published, which is one more reason not to move on this page's account. Compare the shapes properly at team inbox software: a fit framework.

Frequently asked questions

Does Google publish a maximum number of members for a Collaborative Inbox?

No. Google's Groups for Business limits page states "Total membership, per group — Unlimited" and gives no Collaborative-Inbox-specific member ceiling or recommended team size. The limits that do exist are about message activity and invitations, not membership count.

Which Google Workspace editions include Collaborative Inbox?

Google's own pages on Collaborative Inbox and Groups for Business, checked 2026-08-11, do not list which Workspace editions include the feature. The only prerequisite Google states is that Groups for Business must be turned on for the account, and that conversation history must be turned on to enable Collaborative Inbox features.

Can an admin get past the 200-per-session and Groups-UI invitation limits?

Google says the 200-per-session member-addition limit and the invitation and size limits apply only to actions performed in the Google Groups UI at groups.google.com, and that a Groups administrator can add more members using the Admin console or the Google Workspace Admin SDK Directory API instead.

What does Google say happens when a group hits one of these limits?

Google states that reaching one of the Groups for Business limits temporarily restricts the group's activity, and that "Restrictions typically last an hour but can last as long as 24 hours." Google also states these limits "can change without notice to protect Google's infrastructure," so treat every figure on this page as a snapshot, not a permanent ceiling.

Every Google Groups and Gmail fact on this page was read from Google's own documentation and checked on 2026-08-11. Google's own text states these limits "can change without notice," so re-check the current page before relying on a figure operationally. Google, Google Workspace, Gmail, and Google Groups are trademarks of Google LLC; DuoInbox is an independent product and is not affiliated with, endorsed by, or sponsored by Google.