UIDNEXT: The next unique identifier value. The next unique identifier value is the predicted value that will be assigned to a new message in the mailbox. Unless the unique identifier validity (UIDValidity) also changes , the next unique identifier value MUST NOT change unless new messages are added to the mailbox; and the next unique identifier value MUST change whenever new messages are added to the mailbox, even if those new messages are subsequently deleted. The next unique identifier value is intended to provide a means for a client to determine whether any messages have been delivered to the mailbox since the previous time it checked this value.

public long UIDNext { get; set; }

Public Property UIDNext As Long
	Get
	Set

public:
property long long UIDNext {
	long long get ();
	void set (long long value);
}