System will auto-verify the URL when running eBookmark if this function is open. Or the URL must be verified manually (select "verify" from "file" menu). "File" menu is valid after verification.

According to the icons to find if the URL is valid:
The meanings of the icons:
     The valid URL verification passed
     The invalid URL verification failed

Note: The URLs Verification runs in background. So there is nothing changed on the surface. But you can be careful enough to find that:" Last checked date" of bookmark will changed after URLs Verification, "Green check symbol" before the bookmark will change to "Broken chain", Which symbol Icon shows an invalid URL, If its URLs Verification fails.

How to set the verification options refers to Options setting please.