(PHP 5 >= 5.1.3)
imap_savebody — Save a specific body section to a file
Saves a part or the whole body of the specified message.
由 imap_open() 返回的 IMAP 流。
The path to the saved file as a string, or a valid file descriptor returned by fopen().
The message number
The part number. It is a string of integers delimited by period which index into a body part list as per the IMAP4 specification
A bitmask with one or more of the following:
成功时返回 TRUE， 或者在失败时返回 FALSE.