what is the correct salutation when writing a business letter to a Lady?

If you can find out her name (ring the company) you should write:

Dear Ms Surname, if you can not find her name write Dear Madam. Hope this helps.

If she is a lady by title then you use the title but be sure of it and make certain it is not Duchess or Baroness. If you are strictly talking about addressing a female in a letter, the proper way is Dear Ms. _________, unless you know for certain it is Mrs. or Miss and use her last name unless you are on a first name basis with this person prior to the correspondence.

If you know her surname, then 'Dear Mrs Smith'

BUT - being a business letter, is the letter for her attention but still for the business? If so, I am afraid the the salutation should be 'Dear Sir' - but the letter should be marked 'for the attention of.

The reasoning behind this is that the offer is being made to the company and not to the individual.

Sad, but true - the company is still 'Sir!

If you mean a titled lady, it depends on her rank.

For life peeresses and the wives of knights, "Dear Lady Smith".

For Countesses, Duchesses etc. address her by her full title and start the letter "Madam". Ony use the more formal salutation "Most gracious Duchess" etc. if you want her to come and open your garden fete.

To be honest it all depends upon the lady to which you are addressing the business letter. If you don't know much about her, it can be hard to choose. I prefer Madam, no e on the end of it. An e on the end of the word madam, puts things into mind that are far from business oriented. And, when using Madam, do not use her name, use her title. Such as President, Vice President, etc.

Dear Lady (insert name) :

if she is a titled Lady.

If she is just a normal women, and you don't know her marital status then it should be

Dear Madam:

Or Dear (name) :

Make sure you use the colon for all business letters.

For a generic letter to a woman you would use Dear Madam. If you know the woman's last name only, you would use Dear Ms.______. If you knew the first name, you can use Dear <Insert first name here>

You've written Lady with a capital 'L' so presumably she has a title of some description or is the daughter of some such person, therefore you write:

Dear Lady Jennifer, Penelope etc.

Title followed by christian name but don't ask me how to sign off, I think I'd fallen asleep in class by the time we got that far!

Dear Ms or Madam

If you know her full name, say Sarah Brightman,

Head the letter Ms Sarah Brightman, and start the letter Dear Sarah, or just 'Sarah'.

if you only know her surname, Ms Brightman will suit, and if none, madam will do.