Ruby 1.9.2 リファレンスマニュアル > ライブラリ一覧 > library net/imap > class Net::IMAP > thread
thread(algorithm, search_keys, charset)
As for #search(), but returns message sequence numbers in threaded format, as a Net::IMAP::ThreadMember tree. The supported algorithms are:
ORDEREDSUBJECT:: split into single-level threads according to subject,
ordered by date.
REFERENCES:: split into threads by parent/child relationships determined
by which message is a reply to which.
Unlike #search(), +charset+ is a required argument. US-ASCII and UTF-8 are sample values.
See [SORT-THREAD-EXT] for more details.