devise

https://github.com/plataformatec/devise

Ruby

Flexible authentication solution for Rails with Warden.

Mail::Address#domain

Returns the domain part (the right hand side of the @ sign in the email address) of
the address

 a = Address.new('Mikel Lindsaar (My email address) <[email protected]>')
 a.domain #=> 'test.lindsaar.net'

Source | Google | Stack overflow

Edit

git clone [email protected]:plataformatec/devise.git
cd devise
open

Contribute

# Make a new branch

git checkout -b -your-name--update-docs-Mail--Address-domain-for-pr

# Commit to git

git add git commit -m "better docs for Mail::Address#domain"

# Open pull request

gem install hub # on a mac you can `brew install hub`

hub fork

git push <your name> -your-name--update-docs-Mail--Address-domain-for-pr

hub pull-request

# Celebrate!