书信在日常生活及社会事务的处理中，占一定地位。书信作为外事交往的一种重要媒介，仍是我国同世界各国进行友好交往，开展对外贸易，交流情况，沟通思想，增进友谊的主要途径。当然，这仅指一般事务性信件而言。至于书信作为一种社交手段，更是我们日常生活中相互联系的必不可少的一部分。因此，了解书信的书写要求，并认真地写好，就显得十分必要了。
 书信是书面的语言，它起着代言的作用。任何一封简单的书信，都能反映出写信人的思想认识、文化水平和处事态度，都会给人们一种深刻的印象和影响，尤其是涉外书信，由于其本身的特定作用，在外事活动、出国留学、文化交流和贸易往来中，政策问题、业务问题以及方法问题又处于十分重要的地位。因此，书信不仅能够体现出我国的对外政策，也直接关系到我国的政治声誉。所以，要正确有效地处理好这些问题，除了加强本身的学习外，还要有严肃认真的工作态度，这是写好英文书信的基本要求之一。
 当然，写好各种英文书信，并非轻而易举。这不仅要求我们具备较坚实的语言基础，还要求我们了解英文书信的书写格式和行文要求，并在实际工作中，不断地认真实践。只有这样，我们才能写好英文书信，发挥其应有的作用。
 现将英文书信的概况，以及书写方法、行文风格等具体要求，分别介绍如下。
（一）英文书信的种类 (The Kinds of English Letters)
   英文书信大致可分为事务信件（Business Letters）和私人信件(Private Letters)两大类。
由于英文书信涉及面广，用途极为广泛，根据不同的作用和用途，还可细分为社交书信（Social Letters）, 私人信件(Private Letters) 以及一些既属于事务书信又属于私人书信的专门书信（Special Letters）和其他书信(Other Letters), 如表扬信（Letter of Commendation）、感谢信(Letter of Thanks) 等。
 值得指出的事，近年来在社会事务和对外贸易函件的处理中，非正式事务性函件(Informal Business Letters) 已被越来越多地使用。
（二）英文书信的格式 （The Forms of English Letters）
 英文书信，尤其是事务性信件，其书写格式与汉语不尽相同，或者说完全不同。一般来说，英文书信的格式可以分为四种: 并列式/全封式(Blocked Form/ Full-block Format)、 斜列式/全缩式(Indented Form/ Fully Indented Style) 、折衷式/混合式/缩入式（Modified Form / Indented Style）和半封式（Semi-blocked Style/ Semi-block Format）
并列式/全封式 (Blocked Form/ Full-block Format)
并列式亦称全封式，要求信头、收信人地址、称呼和正文（包括每段起行）均上下对齐。如果使用印有信头的信笺，发信日期就要移至左边，齐头写起。由于并列式左边上下齐头，便于打字，故常用于商业信件或正式信函。这些信函多半写给不认识的人，如日常所说的询问信、申请信和投诉信等。（见例1）
 例1：并列式/全封式 (Blocked Form/ Full-block Format)
 
 Madison and Moore, Inc.
 Professional Architects
 7900 South Manheim Road
 Crystal Springs, NE 71003-0092
 January 11, 2001
 Ms. Paula Jordan
 Systems Consultant
 Broadacres Development Corp.
 12 East River Street
 Detroit, MI 48001-0422
 Dear Ms. Jordan:
SUBJECT / Re: Request for alternate duplex plans, No. 32134 (This part can be omitted in informal letters.)
Thank you for your letter of December 3，2000. I have discussed your request with the
officials in our Planning Department and have learned that the forms we used are no longer available..
In searching through my files, however, I have come across the enclosed catalog from a Nevada firm that might be helpful to you. This firm, Nevada Designers, offers plans very similar to the ones you are interested in, as you can tell from the design I checked on page 23 of their catalog.
I hope this will help your project and I wish you success in your venture.
Sincerely yours,
Madison and Moore, Inc.
William Newhouse
Office Manager
Encl.: Catalog
注：(Encl.=Enclosure 附件)

 
例2：斜列式/全缩式 (Indented Form/ Fully Indented Style)
斜列式也称全缩式或阶梯式，要求信头和收信人地址，均比上行缩进一点，呈倒梯形状。正文每段起行，均向右缩进五个字母。

                                              
  246 Wall Street
                                                   New York 5, N.Y.
                                                        June 16th, 1982
 Mr. David Hall
    801 Oxford AV.
       San Francisco
 Dear David,
      I wonder if you have made any definite plan for the coming summer vacation.
 If not, I want you to come and stay with me for a few days. Every member of my
family will be very much pleased to receive you as a guest. You know that we do
not have a magnificent establishment and cannot afford luxuries but if you are
content to share a room with me and do not mind plain food you can be assured
of a hearty welcome and we shall do our very best to entertain you.
 Hoping you will be able to come, I am..
                           
                            Cordially yours,
                             D.  Johnson
  

例3：折衷式/混合式/缩入式（Modified Form / Indented Style）
   折衷式，也称混合式，或缩入式。其信头和收信人地址，上下各自对齐，正文每段起行，向右缩进五个字母。由于折衷式不拘于上述两种格式，书写方便，故目前使用较为普遍。

 
                                                   116 East 59th Street
                                                   Chicago 60637
                                                   U. S. A.
                                                   Mar. 14th, 1982
 Mr. Thomas Ray
 256 Cambridge Street
 London E. C. 2
 England
 Dear Thomas,
          My warmest congratulations to you on your receiving the regional scholarship to
 the State College of Engineering.
 It is an award that you richly deserve. I am sure that you will be a credit to
 the traditions of that fine school and to your chosen profession
 You have my very best wishes for your continued success.
 Sincerely,
                                  
                                   David Brown
    
                                               

 例4 半封式（Semi-blocked Style/ Semi-block Format）
      半封式与并列式/全封式基本相同，每个段落都不缩进，只是将信头及签名缩至中线
 右侧。如下所示。
 
                                             Department of Psychology
                                             The University of Reading
                                             Whiteknights
                                             P. O. Box 217, Reading
                                             United Kingdom
                                             RG 6 6AH
 December 22, 2000
  
    Prof. Li Yang
    School of Humanities
    Beijing University of Aeronautics
    & Astronautics
    Beijing, 100083
    PR China
  Dear Prof. Li,
    It is a pleasure for me to invite you on behalf of the Department of Psychology to
    accept an appointment as a visiting professor at the University of Reading from
    January 1, 2001 to June 30, 2001. The University of Reading will offer you an
    honorarium of ￡1250 per month and reimburse your travel expenses. We hope
    that you can accept this invitation and we ask you to contact Dr. Valerie Peterson
    with respect to details of your research and lecturing activities during your stay in
    Reading.
    I look forward to hearing from you.
   
    Yours sincerely,
 
                                                 Timothy Clarks
                                                 Chairman
                                                 Dept. of Psychology