This is not a direct answer to your question, but: In the case of mass-renaming of email-addresses, you could do it via rails console:
o = "@old_company.com"
n = "@new_company.com"
UserEmail.where("email LIKE ?","%#{o}").each do |ue|
ue.email.sub! o,n
ue.save!
end
If you favor adding a secondary email address:
o = "@old_company.com"
n = "@new_company.com"
UserEmail.where("email LIKE ?","%#{o}").each do |ue|
sm = UserEmail.new
sm.user_id = ue.id
sm.email = ue.email.sub! o,n
sm.save!
end