Email Writing ??

Grammar沒有大問題，但是寫法則不太合適的語氣，你是「請求」而不是「要求」安排另日考試。例如由你一日考試並問老師放便否只會是平等的貿易關才會用的，我想你寫得出這信你也要白領。比較合適的寫法可能是：

If I may ask for a special arrangement for me to take the exam at an alternate date at your discretion so that I may still fulfill my responsibilty on this course.

另外 Australaisa是不是串錯字，澳洲是Australia.

唯一真有錯的地方
I have already phoned you on 11 Jun 2011 and your secretary replied that

我明白你用before的意思是「之前已經...」這種中文想法/文法，但英文have already已經是「之前已經」這時間標記，反而你忘記了寫日期必須要的on a date。還有your已經是「你的」，沒有一個字是「your's」的，你如果見到yours是「你們的」眾數詞-這個好像是小學程度的。

祝你考試安排順利，新婚愉快。

Australaisa - wrong, Australasia -correct (a region of Oceania: Australia, New Zealand, the island of New Guinea, and neighbouring islands in the Pacific Ocean...)
getting marry - wrong, getting married - correct

There are a lot of mistakes in your email. Below is a revised email for your reference.

To :
From :
Subject : Absence of Final Exam

I'm sorry that I shall absent myself the final exam on 16th June,2011 due to my wedding taking place in Australia on the same day. That day is very important beyond all things in my life and also my commitment I made to my fiancee with whom I have fell in love for ten years.

I phoned you before 11 June 2011(?) but your secretary told me that you had been on holidy. Therefore, I send you an email asking you for an approval on my absence . I would much appreciate it if you could specially schedule another exam date for me.

With best regards,

I am looking forward to your reply.

Raymond Lai (Student of Class No.008)

2011-04-12 22:19:29 補充：
Correction: ... with whom I have fell in love for ten years. -----> ... with whom I have fallen in love for ten years.

Subject : Final exam
Dear : Mr. Tang

I am pleased that we will be going to final exam on 16 June 2011, but I cannot attend on that day, I promise my fiancee that we are getting marry on the same day in Australia.

Our wedding is important for me because Jenny and I have fell in love for ten years. I do not want to lose my lover. I have already phoned you before 11 Jun 2011 and your secretary replied that you were away on hoilday, so I am typing this email to you.

If it is convenient, I would prefer to have the final exam on 19 June 2011, I will appreciate it if you could confirm the date as soon as poossible.

I am looking forward to receive your reply.

Regard
Raymond Lai
Student of class 008.