mutt-1.5.21p0v0 to read my mail on OpenBSD 5.2 every now and then.
mutt show question marks instead of Cyrillic characters when I open standards-compliant email messages in Russian?
You have to decide on a locale and a character set.
For a list of locales and their corresponding character sets, see
/usr/share/locale/ on OpenBSD. There is no mix-and-matching between languages and charsets, apart from what's in that directory. However, the language and charset are controlled by
LANG and various more specific
LC_ environmental variables, which can be set independent of each other to potentially have the exact effects desired.
In order to just change the character set, and not the language of the menus or any other options, only
LC_CTYPE has to be modified. For example, in PuTTY Window → Translation, set
Remote character set to either KOI8-R or UTF-8, and then run
mutt as either
env LC_CTYPE=ru_RU.KOI8-R mutt or
env LC_CTYPE=en_US.UTF-8 mutt (assuming a C-shell), respectively.