Make the standard Devise confirmation email our new plaintext version

app/views/devise/mailer/confirmation_instructions.html.erb

-<p>Welcome <%= @resource.name %>!</p>
-
-<% if @resource.unconfirmed_email.present? %>
-  <p>You can confirm your email (<%= @resource.unconfirmed_email %>) through the link below:</p>
-<% else %>
-  <p>You can confirm your account through the link below:</p>
-<% end %>
-
-<p><%= link_to 'Confirm your account', confirmation_url(@resource, confirmation_token: @token) %></p>

app/views/devise/mailer/confirmation_instructions.text.erb

+Welcome, <%= @resource.name %>!
+
+<% if @resource.unconfirmed_email.present? %>
+You can confirm your email (<%= @resource.unconfirmed_email %>) through the link below:
+<% else %>
+You can confirm your account through the link below:
+<% end %>
+
+<%= confirmation_url(@resource, confirmation_token: @token) %>