I want to send emails in a number of languages (en/es/fr/de/ru/pl). I notice that Gmail uses KOI8-R charset when sending emails contatining Cyrillic characters.
Can I just use KOI8-R for ALL my emails, or is there any reason to select a particular charset for each language?
i would recommend alway using utf-8 nowadays.
wikipedia on utf-8:
UTF-8 (8-bit UCS/Unicode Transformation Format) is a variable-length character encoding for Unicode. It is able to represent any character in the Unicode standard, yet is backwards compatible with ASCII. For these reasons, it is steadily becoming the preferred encoding for e-mail, web pages,[1] and other places where characters are stored or streamed.
Use UTF-8. KOI8-R wouldn't be ideal for non-Russian languages, and changing codesets always tends to be a headache on the receiving side.