On a daily basis I'm creating campaigns in English, most Latin based languages (Spanish, Italian, French), Russian (Cyrillic), Arabic and Chinese. UTF - 8 seems to be working well across most browsers and email-clients.
Only exception: Lotus Notes but I'm not loosing any sleep over it.
Of course you need to figure out what browsers/email clients your customers use to open/read your campaigns.
EDIT: If you are having problems try looking at your email header and what Content Type your ESP sets when sending your campaigns.
On a daily basis I'm creating campaigns in English, most Latin based languages (Spanish, Italian, French), Russian (Cyrillic), Arabic and Chinese. UTF - 8 seems to be working well across most browsers and email-clients.
Only exception: Lotus Notes but I'm not loosing any sleep over it.
Of course you need to figure out what browsers/email clients your customers use to open/read your campaigns.
EDIT: If you are having problems try looking at your email header and what Content Type your ESP sets when sending your campaigns.
I agree that the important first step is to check your headers.
While you can set the character set via a meta tag in the content of your email,
it's my understanding that most email clients rely more on the character encoding described in the header of your email.
The 100% working solution is to convert the non-latin characters to entities.
That's a great tip. Here's an exhaustive list of entity codes for those interested:
http://dev.w3.org/html5/html-author/charref
Having dealt with this headache more times than I care to remember, HTML entity codes are the way to go.
as Jason said - you need to ensure your ESP is/can encode as UTF-8 in the header of the email (as well as the header of your html)