result of uid sort by subject

Result of uid sort by subject is not expected. for example: Japanese => English => Japanese => English I'm now using Dovecot 2.2.31.

command example: HNKK6 UID SORT (REVERSE SUBJECT) utf-7 ALL

• SORT 3 1 7 2 4 10 11 8 12 HNKK6 OK Sort completed (0.002 + 0.041 + 0.001 secs).

Any hint?

-- Masashi Astro TACHIBANA QUALITIA CO., LTD. mailto:tachibana@qualitia.co.jp