See About Google Groups.

The Google Groups for Business service is similar to the free version of Google Groups, but was designed to work specifically with the enterprise environment. See the Google Groups for Business administrator FAQ for questions related to the business version.

With Google Apps, you can create up to 10 groups. With Google Apps for Business and Education, you can create as many groups for your organization's account as you like.

With Google Apps, a group can contain up to 100 members. With Google Apps for Business and Education, there's no limit to the number of members a group can have. However, if the group contains external members, note that there is a limit to the number of messages you can send to external recipients per day (see next question).

Yes, to fight spam and email abuse, Google limits the number of messages you can send at once to external recipients. If you send a message to a group, each external member is counted as one recipient.

Learn more about email sending limits

Learn more about best practices for sending a large amount of email through Gmail

Yes. Also to fight spam and email abuse, Google limits the number of messages sent to any single group within a short period of time. This limit applies to messages sent over email or posted via the web.

Learn more about group posting limits

Yes, a user can be direct member of up to 2000 groups. A user is a direct member of a group if his or her address was added directly to the members list. A user can also be an indirect member of a group -- that is, an owner of a group or a member of a group that's nested within another group. A user's total group memberships -- both direct and indirect combined -- can be up to 5000. Learn more about group members and owners

Yes, the maximum size limit for messages sent to a group is 25 MB, including attachments (the normal Gmail limit). Group owners or managers can edit specific groups to set lower size limits.

You can't send or forward non-delivery receipts (NDRs) -- also called "bounce messages" -- to a group. Messages that resemble NDRs are also not permitted.

Yes, when creating a group with the Admin console, you can choose which of your domains you want to use for the group's email address.

By default, the group email address is generated from the group name, in the form: group-name@your_domain

For example, a group of sales at domain example.com will have a default email address of: sales@example.com

You may modify the default address via the group's settings.

You have the option of allowing people outside your domain to send messages to a group. If a malicious sender knows that group's address, members of the group might receive more spam. We strongly recommend that you carefully consider the options you choose for any groups you create.

To improve spam filtering for a specific group, you can change the Group's Spam moderation settings.

Currently, a group appears in Contacts, under All Contacts, only after you send a message to that group.

Yes, just start typing a group address in an email message or calendar invitation, and the address will be completed automatically.

No. If you send an email message or meeting invitation to a group, recipients see only the group name (rather than individual names or addresses) in the To line of the message or invitation.

If you invite a group to a meeting, all of the group's members appear in the invitation on your calendar only if you have the appropriate access permissions for that group. This limitation upholds the privacy settings for a group, and it applies to both users and administrators. Learn more

Yes, a group can also contain the addresses of other groups, so you can use groups as building blocks for larger groups. Learn more

Yes, message moderation is available if you enable the Google Groups for Business service.

Yes, the Provisioning API (2.0 or later) supports provisioning of groups. Learn more

Yes, you can use either Google Apps Directory Sync or the Google Provisioning API to migrate groups (mailing lists) on your LDAP server to Google Apps. Learn more

Yes, the Google Apps Service Level Agreement applies to the Google Groups component of your Google Apps service.