Make a forum and in it put a single locked topic consisting of the emails of all members in comma delimited text. You can create this by running the following SQL and saving its output as CSV.
Code: Select all
SELECT user_email from phpbb_users WHERE user_type <> 2
If your table prefix is not phpbb_, change accordingly.
Then, at the top of that topic, explain they can use those emails to either make a group in their email client, or cut and paste them into an email message.
Otherwise, what you want would require a MOD, and MOD Requests are closed for version 3.0.x.