Modern business communication should be in plain, clear English.
An example of plain, clear English is this:
A: Could you please fill out form 4B and return it to us?
What we wish to avoid is this:
B: You are hereby requested that, in order to facilitate the application process, form 4B must be completed in full and returned to us at your earliest convenience.
Example A is direct and uses normal, plain language. We could just as well use the sentence in spoken English.
Example B is too long. It uses old-fashioned language, such as ‘hereby’. It uses passive voice where it is not necessary. The writer seems to be making a conscious attempt to make the sentence longer and to use unusual words.
A sentence length of around 15 words on average is desirable. Long sentences just make business correspondence more tedious to read.
We wish to be polite without being longwinded. If you use language such as ‘please’, ‘thank you’ or ‘could you…’, it is polite enough. Try to use friendly, warm language, such as ‘happy’ or ‘pleased’. For instance:
I would be very happy to accept your invitation.
Years ago, business writing was more formal. Not many people attended college or university and they desired to show that they were educated by using very formal language. These days, most people are highly educated and the most important thing is time. If you write old-fashioned, longwinded messages, then you are wasting the other person’s time, and that is not polite.
To learn more about plain English, try this site: http://www.plainenglish.co.uk/free-guides.html