How to write formal letters

Structure of a formal letter
the example letter below shows you a general layout for a formal letter

The formal letter should contain:
Sender's Address
Date
Inside Address
Suitable grammar structures
Level of politeness, formality
Linking words

Rules for writing formal letter
In English there are a number of conventions that should be used when writing a formal or business letter. Furthermore, you try to write as simply and as clearly as possible, and not to make the letter longer than necessary. Remember not to use informal language like contractions.
Addresses:
1) Your Address
The return address should be written in the top right-hand corner of the letter.
2) The Address of the person you are writing to
The inside address should be written on the left, starting below your address.
Date:
Different people put the date on different sides of the page. You can write this on the right or the left on the line after the address you are writing to. Write the month as a word

Salutation or greeting:
1) Dear Sir or Madam,
If you do not know the name of the person you are writing to, use this. It is always advisable to try to find out a name.
2) Dear Mr Jenkins,
If you know the name, use the title (Mr, Mrs, Miss or Ms, Dr, etc.) and the surname only. If you are writing to a woman and do not know if she uses Mrs or Miss, you can use Ms, which is for married and single women.
Ending a letter:
1) Yours faithfully
If you do not know the name of the person, end the letter this way.
2) Yours sincerely
If you know the name of the person, end the letter this way.

Introduction
Introduction should be short and state the purpose of the letter- to make an enquiry, complain, request something, etc.

The main body of letter
The main body of the formal letter should clearly state the points that you want to make in your letter. As a general rule it is a good idea to keep this as to the point as possible to ensure that the recipient remains engaged. Longer letters may be more appropriate when making a complaint as you may require to add more detail in order to convey the importance of what you are putting across.

Conclusion and the end of letter
The concluding paragraph of a formal letter should outline what action you would like the recipient to take: to make a refund, to send you information etc.

Linking words
Beginning:
first/ first of all/ secondly/ thirdly …
Reinforcement:
above all/ actually/ in addition/moreover/as well as/ furthermore/then/what is more
Comparison:
also/both …and ../likewise/ in the same way
Summary:
altogether/in conclusion/ to sum up/ all in all/thus/therefore

Abbreviations Used in Letter Writing
The following abbreviations are widely used in letters:
asap = as soon as possible
cc = carbon copy (when you send a copy of a letter to more than one person, you use this abbreviation to let them know)
enc. = enclosure (when you include other papers with your letter)
pp = per procurationem (A Latin phrase meaning that you are signing the letter on somebody else's behalf; if they are not there to sign it themselves, etc)
ps = postscript (when you want to add something after you've finished and signed it)
pto (informal) = please turn over (to make sure that the other person knows the letter continues on the other side of the page)
RSVP = please reply