imap_uid

This function returns the UID for the given message sequence number (PHP 3 >= 3.0.3, PHP 4, PHP 5)
int imap_uid ( resource imap_stream, int msgno )

This function returns the UID for the given message sequence number. An UID is a unique identifier that will not change over time while a message sequence number may change whenever the content of the mailbox changes. This function is the inverse of imap_msgno().

注意:

This is not supported by POP3 mailboxes.

See also: imap_msgno().