I have my logbook search online, powered by HRDLOG.net. You can see my last 10 QSOs, but more importantly you can enter your call sign and you will be able to see if we have worked each other, what band, mode, date and time. I do QSL electronically via LOTW and eQSL, as well as direct by post and the bureau.
I do QSL 100%, but am quite behind in sending cards out. Any card received is answered immediately. You do not need to include green stamps, IRCs or an SASE. I am of the opinion the QSL is “the final courtesy.” I upload my log to Logbook of the World on a daily basis, as well as eQSL after a QSO was made.