PROPER ADDRESSES: Sz.P., W.P., P.???

What is the proper way to address a letter/envelope in Polish? One sees all kinds of variants including:

Sz.P., Sz. Pani., Sz. PP.
Szanowny Pan, Szanowna Pani, Szanowni Państwo
W.P., W. Pan, W. Pani etc.
Pan, Pani, Państwo
...nothing (no titles)...

as in

W.PP.
Anna i Edwarda Mikołajewscy
ul. Dworcowa 7/8 or 7 m.8
01-230 Warszawa

PP.
Anna i Edwarda Mikołajewscy
ul. Dworcowa 7/8 or 7 m.8
01-230 Warszawa

Anna i Edwarda Mikołajewscy
ul. Dworcowa 7/8 or 7 m.8
01-230 Warszawa

Sz.Państwo
Edwardostwo Mikołajewscy
ul. Dworcowa Nr 7/8 or 7 m.8
01-230 Warszawa

also should the title (if used) be above or on the same line as the names:

Sz.Pan
Jędrzej Srajda

or

Sz. Pan Jędrzej Srajda
or simply

P. Jędrzej Srajda

I'd go with
Sz.P.
name + surname, below, not in the same line.


(or similar, stands for Wielmożny/-a/-i Pan/Pani/Państwo)
it's rather antiquated, social conditions changed, so we don't use the expression Wielmożny Pan anymore, unless in an ironic or joking context.


I'm not sure, but 7 m.8 is more precise, because 7/8 may sometimes be misleading (when a large real estate has a double number, meaning it occupies what previously was Dworcowa 7 and Dworcowa 8, although in that case it would be better to write Dworcowa 7-8)

also m.8 (mieszkanie 8) stands for an "app.", when you write to an office or a company you rather use p.8 (pokój 8) for

a "room".


that's a big no-no, you don't want to sound as some pre-war chauvinist male pig, do you?