I recently imported a CSV file and everything worked perfectly, except:
3 email address were rejected as being bad.
All 3 email have the same format - example:
john.o'smith@something.com
It appears that the apostrophe in the name caused the problem. I used to think an apostrophe was not allowed in an email name but they are!
I know this becuase one of the names rejected happens to be a friend of mine. I just confirmed her email address (by sending an email) and the address works perfectly. She says that she has had the email address for a couple of years without any problems.
I assume the code checks the imported email addresses for invalid characters (?) and rejected these becuase of the apostrophe.
This IS NOT a big problem for me, but I did want to pass on this information.