I use Ham Radio Deluxe for my Radio Control and Logging functions. I personally like the features it offers, integration with eQSL, hrdlog.net, LoTW, etc. This page is brought to you by hrdlog.net.
Here you can search for your callsign if I have made a contact with you. It should also show whether or not a QSL card has been sent or received.
Please note: I use eQSL for most contacts, but if your call is one I need for an award or something I will send a physical card, and hope you send me one too. Also all special events and DX contacts are sent physical QSL cards.