There was such a need, because I wanted to make e-mail distribution a third-party service to my forum users on phpbb, bypassing the internal capabilities of the forum.
For successful downloading and copying of e-mail users in the popular phpBB conference it is possible to execute the submitted SQL query to the database, for example, using the web-interface phpMyAdmin
SELECT `user_email` FROM` phpbb_users` WHERE `user_email` <> ”
then the system will ask you to view the entire list or export the file to yourself