addressing a letter in Japanese?

OK, so I have what might be a simple question. I am going to send a postcard to a penpal who is Japanese and I know how to address the letter as far as the actual address goes (crazy system in Japan) but I would like to know how to include the honorific 'san' at the end. I have read that sometimes the 'さ'is dropped and only 'ん' is used at the end. Or is 'さん' more appropriate? Also, 'さん', is written in hiragana while names use kanji. Do I mix the two since 'san' written in kanji would be '三' which is the kanji for three if I am correct?

Also, spaces in names, are there any? I have always been under the impression that there are since the kanji in names can be hard to separate between the last and first names. So is there a space between the last and first name then the hiragana 'san'?

So is it:

(kanji)lastFirst(hiragana)san
松本美羽さん

or is it:

(kanji)last (kanji)first (hiragana)san (note the spaces)
松本 美羽 さん

and would it be with or without the dropped 'さ'
like 松本美羽ん

My best guess is: 松本 美羽さん

I have tried Google but I have found no clear answer. Yea, Yea, I know I can just use English and the letter will get there no problems. I have send many a letter this way so I know there is no issues there :) I promised to try and embarrass myself and use Japanese next time and want it to be a surprise.

Thanks for your help in advance.

On letters, it is "sama," not "san." I don't know where you heard dropping the "sa," but I have never heard of that at all... If you are ever to use "san," it should be in hiragana, never with the kaji for "three." Crazy system it might seem to some people, but it makes sense in Japan.

松本 美羽様
松本美羽様

You can put in the space or not between the family name and given name.

AK is correct- I don't know where you heard that the "sa" is dropped (Maybe when talking about someone's home, as in "鈴木んち"?), but this is never done on letters.

There are many kanji with the sound "san" other than 三, but that's irrelevant- if it's the title that goes after somone's name it's only ever written in hiragana. As AK said, for letters people use "sama" (様) anyway.

I see about the "n" thing now, Sira, thanks :)

There is a cartoon series called あたしン家, pronounced "atashi'n chi," meaning "my home" even - that "n" is not really "sa" dropped off from "san," but "no" (and the following "u" of the word "uchi") shortened into "n".

Thank you for the clarification. I only read that the 'sa' was dropped in one forum and it was really confusing me. So 'sama' is always used no matter how well you know someone as far as the address on a letter is concerned?

Thanks again.

Yes, in the address on the envelope/postcard, it's always "sama" 様. Some people (girls) might choose to write さま (in hiragana) intentionally for very close friends (for somewhat *cute* appearance/effect) but that's about the only exception I can come up with.

(Of course, in the opening of the letter (main text) itself, you can use "-san" or that person's nickname, etc., whatever you refer to each other with.)

That makes me think of something: if you write your letter on one sheet only, i suggest you include a second blank paper in the envelop. Since you seem to want to make it right ;) This is a traditional japanese custom... kind of a way to say "i'm sorry i wrote only one page". just so you know :p

Thank you all for your responses. This clears up all of my questions.