Multiple error messages to be shown in an EXIT

I have a requirement to validate selected Line items when save button is clicked in MIRO. Inside the Loop i used the MESSAGE statement with type E but the problem is system is showing only first selected line item validation message only. after that another line item messages are not showing.

The requirement is to add error messages to a message LOG and to show it along with standard messages in messages POPUP. Could somebody provide me the steps to acheive the same.