Send and recieve issue

Hello,

Today, It looks like I have a sudden issue with sending and receiving mails. I am using zoho mail for a while and no issues. I have sent a message form my yahoo account to zohoo and visa versa and i did not get a failure message in both mail system. Still I can not see my mails in my yahoo as well as zohoo inbox. can one please explain what is happening.

Alla accounts from zohoo are affected

Regards