Just returned from this trip(GREAT !!!), however ran into a bit of a snag

I had only taken my original printed itinerary(May 07) showing a 4:15p departure from SYD with me.
Imagine my surprise when I showed up back at the airport at 2pm(Bondi Explorer), went to the counter to check on available upper deck seating(NO)- chose 25A over my 6A assigned and agent says good timing for the 2:30 boarding. DO WHAT??? OS, well UA had changed the schedule-REALLY bad on my part for not printing a more current itinerary(Won't let that happen again)

So anyhow, I grabbed some postcards from the Quay but was unable to get them written and mailed before take-off(after all ANZ Lounge was a priority)
So am looking for someone that I can mail them to here in the States and you'll drop in a Sydney mail-box for me. Prefer as soon a date as is possible.
PM, please

Thanks
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They are already stamped, just would like an Austrilia post mark on them