congrats, Matt ! I upgraded to Extra last year after over 20 years Advanced class.
Saw some other comments and hope I am not off-base and out of context without reading everything, but ever so often I receive an eQSL requesting confirmation for a QSO and I look up the call - usually a QSO from a good while back - and I see that it is someone I worked under an old callsign. I can't acknowledge it because it's like double dipping to me. Example, if I change my call from KT4EP to something else, it wouldn't be ethical or correct to go back and try to send out eQSLs to everyone I made a contact with as KT4EP with my new callsign. I believe one might have to create a new eQSL account for the new callsign? Ditto for LoTW?
