通常商务交流中的书信书写格式分为四种，每一种都有其突出的地方，而选择用哪种格式则看写信人的爱好了。

Modified-Block Letter Format

In this format each typed element - except the date and the signature block - begins at the left-hand margin. The date may be backspaced from the right margin point to align at the right margin; it may be centered, or it may begin at the center. （日期可以放在最右边，也可以放在中间，或是从中间向右写。）The most attractive placement of the date, however, may depend on the letterhead design.

Semi-Block Letter Format

This format resembles to the modified block in every other regard except that the paragraphs in the body of the letter are indented.（这种格式的排版，除了书信主体每段首行要空格以外，其他均类似于Modified-Block Letter。）

Full-Block Letter Format

The full block format is illustrative of the trend toward simplicity and ease of use. All lines, including the date and the signature block, begin at the left margin. Paragraphs are always blocked. （段段之间通常空行。）

This letter arrangement is more efficient than the modified block or the semi-modified block in that no extra time is required for paragraph indention or placement of the date and closing lines. In addition, many writers believe that the full-block arrangement provides an attractive, business-like appearance.

Simplified Letter Format

As in the full-block format, all lines in the simplified format begin at the left-hand margin. It leaves out the conventional salutation and complimentary close, invariably containing a subject line in lieu of the salutation indicating what the letter is about（在本来该写称呼的地方增加一句表明信的内容的主题句）. Supporters of the simplified format argue that salutation and complimentary close contribute little to the message except for a waste of time. Others, however, are reluctant to omit the tonal qualities of the two components because they have been used routinely over years and readers expect them.

（来源：竞学网 英语点津 Annabel 编辑）