Soft Bounce

Can anyone tell me why an email would “Soft Bounce”? This is a family member who just joined our club in June and we just realized that he isn’t getting my emails. He received my first three emails and then nothing after that. His email address hasn’t changed, I ran the list builder and downloaded the CSV file and his contact is there and says that he has 10X Soft Bounces. What can I do to fix it, what caused this?

Variety of reasons…their email service is down, their mailbox is full, they use Earthlink… It’s usually on their side.