Strange Horizons received its first fiction submission on 27 June 2000, ten years ago today. It was from a friend of mine. The next one didn't arrive until 29 June; then we had an amazing high-volume day on 30 June, with five submissions! (Nowadays we get about 15 or 16 a day on a normal day.)
The first submissions we received that we ended up buying didn't arrive until 1 July: a couple of pieces by Bruce Holland Rogers.
Also of note in those early days of submissions: A story from one Timothy Pratt, of North Carolina, addressed to "Ms. Mohanraj" (which I mention only because it suggests that he didn't know Mary Anne at that point).