I've been getting more and more of them.  Many from Canada of late.  I just file them in my email folders by continent/country.  None have been checked to see if they are in my log.  Not worth the effort, kinda like all the eQSL "requests for confirmation".  Most of those were not in my log, so I stopped posting to eQSL and the requests stopped.  

I've noticed several hams have stated that they will NOT respond to these QSL's.  I won't unless I get a real QSO card, but with postage rates increasing worldwide, this type of QSLing may become more accepted.  I'm still using the last roll of several 100's I bought about 10 years or so ago.  I think they are really $.29 postage rates, but "Forever" stamps.