(PHP 4, PHP 5)
imap_close — Close an IMAP stream
Closes the imap stream.
由 imap_open() 返回的 IMAP 流。
If set to CL_EXPUNGE, the function will silently expunge the mailbox before closing, removing all messages marked for deletion. You can achieve the same thing by using imap_expunge()
成功时返回 TRUE， 或者在失败时返回 FALSE.