I just had the same problem importing a mailing list with 206 addresses (100% correct and consenting addresses), and the silent fail was quite frustrating. How about showing to the user WHICH email adresses are supposedly fake or wrongly formatted? Also, why can't the process be completed if any one of the emails is wrong?? doesn't make really make sense to me.
ANYHOW, I was able to solve the problem by splitting my csv file into multiple files with 50 entries each and uploading each one separately, the thought behind it being that I could find the culprit address that way. In the end I was able to successfully upload all the files and there was no error message. Hope this helps anyone who may have the same problem!