We’re all aware of the length of time some QSL cards take to appear. For instance, an envelope appeared at my club about 6 months ago with which contained QSL cards that were between 10 and 12 years old!
Now from the ridiculous to the sublime…
I had a QSO with DO2AT on Monday 4 April at 1301z. His QSL card arrived on Tuesday 5 April at 1230z… Now, quite how this QSL card attained what can only descriped as warp speed, beats me.