Allow automatic group membership based on subdomain

Continuing the discussion from Automatically add users to group based on part of email domain:


At the minute the group membership setting “Users who register with an email domain that exactly matches one in this list will be automatically added to this group” – where the admin wants to match – only matches second-level domains like

I propose that this be changed also to match subdomains, e.g.


  1. It would not be feasible for me manually to type in the subdomains for two government-related domains in particular: each has hundreds of subdomains, which are constantly changing, and the full list is not publicly available.

  2. It would provide consistency with email_domains_whitelist, as noted by @sam in Automatic registration domain wild card - #3 by sam

    Yeah there is an inconsistency internally, our automatic group membership is based off a strict domain match per:

    discourse/automatic_group_membership.rb at 40546af21746d469e39dfdcc9ca48987fef6cf3c · discourse/discourse · GitHub

    Our matcher for the email_domains_whitelist uses this match

    discourse/email_validator.rb at 40546af21746d469e39dfdcc9ca48987fef6cf3c · discourse/discourse · GitHub

    I think it makes sense to make this coherent and consistent.

    @techAPJ can you adjust the group regex… carefully and make sure it is tested so it also allows subdomains.

Proposed solutions

This is possible by a minor amendment to pattern = "@(#{domains.gsub('.', '\.')})$" at discourse/discourse/blob/20de49c8722f8e50e93732702a8d06570376edcd/app/models/group.rb#L1017

  1. Changing this to pattern = "@.*(#{domains.gsub('.', '\.')})$" worked for me when I tested it on my forum.

  2. I imagine that pattern = "@(.+\\.)?(#{domains.gsub('.', '\.')})$" (based on email_domains_whitelist) would also work but I only noticed that later and haven’t tested it. I don’t understand why it’s not (.+\.)? but maybe the \\ is a Ruby thing.

An alternative (if you were worried about users who currently intend to exclude subdomains from automatic membership) would be to allow wildcards, e.g. to type * for automatic group membership.


Thanks for considering this request.