OUTLOOK EXPRESS 收不到1.5MB容量

我公司的我的OUTLOOK EXPRESS以往可收至3MB至4MB圖,但本星期收不到1.5MB以上圖,會出現以下訊息.
A message was sent to you that was returned to the sender(bounced)
because it would have caused your mailbox quota to be exceeded.

The following is the reason that the message was over quota:

Quota Type: total bytes stored
Quota Available: 2121440
Total Quota: 20971520

我己冊除我OUTLOOK EXPRESS的收/出件匣,備份匣內檔案也沒用.
是否在那可減去我的OUTLOOK EXPRESS容量比其它同事?因其它同事沒此問題.....或我可怎較回大些容量呢.
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