1) Use the option max_users

badlop — Wed, 20 Jan 2016 10:53:10 +0000

1) Use the option max_users in your ejabberd configuration file. Look in the Guide for examples.

2) Sorry, I don't understand the question.

3) Try something like this. It will allow only to register usernames with characters between a-z, and numbers:

In ejabberd 3:

acl:
  ascii:
     user_regexp: "^[a-z0-9]*$"

access:
  register:
    ascii: allow
    all: deny

In ejabberd 2:

{acl, ascii, {user_regexp, "^[a-z0-9]*$"}}.
{access, register, [{allow, ascii}, {deny, all}]}.

ejabberd - Comments for "problem with ejabberd 2"