PSYC is currently encoded in Unicode/UTF-8. You can provide a _charset PSYC variable should your body be encoded differently, but variables must be in UTF-8.

psyced has been fixed to no longer attempt any charset conversions for native PSYC clients.

Character Sets & Encodings

Binary data encoding

<Monkey> As an alternative to base64, yerac points out Ascii85 encoding, a more compact method of encoding binary data in ASCII format (Essentially, it's just base 85 encoding instead of Base 64)

... only of relevance when we cannot do straight transparent binary data interchange.