Websites and email clients use certain character sets to interpret international symbols, like ñ and é. Mailchimp aims to accommodate many languages, and supports three character sets in campaigns and lists: Unicode (UTF-8), ASCII, and extended ASCII.
Although there is some debate about character sets and encoding schemes, Mailchimp relies largely on UTF-8. If you use non-ASCII characters that aren't UTF-8 encoded, you could encounter errors in your campaign layout or list segmentation.
Managing character sets in different applications varies a great deal, so we encourage you to search the web for instructions on how to manage character encoding with your preferred word processor or spreadsheet application. When your documents are set to UTF-8, Mailchimp will be able to appropriately render content you insert or upload to our system.
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.