No, never, Yahoo mail down can’t block your emails. But, you can see that if this issue occurs, then you become unable to access your account. Actually, this issue occurs due to various reasons. Either you have internet issues or there are some changes at the world level. Actually, if any bugs found and the team goes to resolve them, then it is possible that you suffer to access your accout for a couple of moments. https://www.contact-customer-service.net/blog/yahoo-mail-down/