Where did you get so many postcards? I have written to many postcrossers from infrequent sources, some of them have not been online for several years, others simply do not respond.
Effort and luck
(1) Forum exchange of PC
(2) Ask traveling friends to help send it out
(3) Stick stamps and prepare cards by yourself, put them in an envelope, and send them to the post office to obtain a postmark
Few days ago this postcard from Trinidad and Tobago arrived at home:
https://www.postcrossing.com/postcards/SJ-1843
I received an official postcard from Svalbard today 
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