app/views/user_mailer/changeemail_already_used.text.erb
<%= _('Someone, perhaps you, just tried to change their email address on ' \
'{{site_name}} from {{old_email}} to {{new_email}}.',
:site_name => site_name.html_safe,
:old_email => @old_email.html_safe,
:new_email => @new_email.html_safe) %>
<%= _('This was not possible because there is already an account using ' \
'the email address {{email}}.', :email => @new_email.html_safe) %>
<%= _('The accounts have been left as they previously were.') %>
-- <%= _('the {{site_name}} team', :site_name => site_name.html_safe) %>