高水位线是段中已用和未用空间的边界。

The high water mark is the boundary between used and unused space in a segment.

“收件箱”的低水位线值必须小于高水位线值.

The Inbox low watermark value must be smaller than the high watermark value.

“已发送传真”文件夹的低水位线值必须小于高水位线值.

The Sent Items folder low watermark value must be smaller than the high watermark value.

“已发送邮件”文件夹高水位线不能等于零.

The Sent Items folder high watermark cannot equal zero.