Hi Anon
You can by all means have a lot of in
tent in your letter but no indention is necessary these days. (Just referring to a previous reply.)
I have got(ten) the impression from my British friends' letters that commas are out of style in British English. (However, I don't know your nationality at all.)
In BE most up-to-date people don't use commas after
Dear Sir and Yours faithfully. They don't even use commas in dates nowadays: January 10 2007. Americans are another breed. They want you to put a comma after
Mr in
Mr. Smith.
It's a free world (at least to an extent). Take your pick.
Cheers
CB