3、With reference to our telephone conversation today... 

关于我们今天在电话中的谈话... 

4、In my previous e-mail on October 15... 

先前在10月15日所写的信... 

5、As I mentioned earlier about... 

如我先前所提及关于... 

6、as indicated in my previous e-mail... 

如我在先前的信中所提出... 

7、As we discussed on the phone...