Incoming Emails Problem

I am attaching a screenshot of my emails that are being Accepted and appear in the Success list. The problem is I am not able to view these emails - I use Webmail (Round Cube as a client) and many of the emails are not there. Of course they do not download to my outlook as well. The problem appears to be with emails that are auto generated. For example, when I signed up this forum - a link is emailed for confirmation. I never received the link in my Webmail. I had to Register again with my Yahoo account. Please advise.