1、在B1單元格輸入“=LEFT(A1,FIND("X",SUBSTITUTE(A1,".","X",3))-1)&"."&RIGHT(A1,LEN(A1)-FIND("X",SUBSTITUTE(A1,".","X",3)))+1”。（最外邊引號不要輸入）回車
2、鼠標移動到B1單元格右下角，光標變為黑十字，點住左鍵向下拖拽即可。
假設原數據在A列
B1輸入公式
=LEFT(A2,FIND("@",SUBSTITUTE(A2,".","@",3)))&RIGHT(A2,LEN(A2)-FIND("@",SUBSTITUTE(A2,".","@",3)))+1
下拉即可