MailChimps brief article about it: http://kb.mailchimp.com/accounts/management/international-characters-in-mailchimp http://kb.mailchimp.com/accounts/management

MailChimps brief article about it: http://kb.mailchimp.com/accounts/management/international-characters-in-mailchimp http://kb.mailchimp.com/accounts/management/international-ch... "Note Although MailChimp can process UTF-8 characters in most parts of our application, we cannot process UTF-8 characters in your subscribers' email address prefixes. We do accept Internationalized Domain Name (IDN) servers, so it’s alright to have UTF-8 characters in the domain name. For example, we’ll block direcciónelectrónica@domain.com because the international characters are in the prefix, but we'll allow an address like test@ñoñó1234.com, where the characters are in the domain."