Google-groups – Max users to receive emails in Google Groups

Well, you asked it on 2011 and Google Groups changed recently some features...

But if you want to enable replies from all users on the new Google Groups interface (hey, I use it in Portuguese, so some words here would be synonyms of real options):

1. Enter the group and choose Manage

2. On Details > E-mail Options, change Post Answers to All Members, and press Save

3. On Details > New Members, check the checkbox New Users can Post, and press Save

4. On Permissions > Basic, on Post select All Members, and press Save

5. On Permissions > Post, on Post select All Members (if you have done 4th step, probably this one would be already done too, but once, when I was creating dozen of new groups, options from these steps, 4 and 5, were different, perhaps a momentary bug), and press Save

6. On Info > General, on Post Options, check the option to Allow E-Mail Posting

7. And finally, on Members > All Members, check if someone is not allowed to post (on Posting column). If so, select them and on Actions > Post Permissions select the default option.

You can find a lot of the relevant info in the Google Groups FAQ.

For example, the maximum group size is dependent on the type of Google Group you have:

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).

And attachment limits:

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.

More info about messages and attachments can be found on this Google message FAQ.