app/views/devise/mailer/confirmation_instructions.text.erb
Welcome <%= @resource.display_name || @resource.to_param %>!
You can confirm your account email by visiting the following URL:
<%= confirmation_url(@resource, confirmation_token: @token) %>
Your confirmation token is: <%= @token%>
You can access your unconfirmed account for <%= (Devise.allow_unconfirmed_access_for / ActiveSupport::Duration::SECONDS_PER_DAY).to_i%> days.