The internet service certificate is not trusted. Do you want to take corrective action now?

Issue
In Lotus notes By default, messages that contain links to secure web pages trigger a pop-up warning that begins, "The internet service certificate is not trusted. Do you want to take corrective action now..."

Explanation
Internet root authorities, such as VeriSign, are companies whose business is to sell certificates. Setting Notes to trust Internet root authorities stops the pop-up warning for web servers secured by a certificate from one of these companies. If you see this pop-up warning after setting Notes to trust Internet root authorities, the message may contain a link to a harmful web page. Check with the sender before opening it.

Solution

• Select Security from the File menu, then select User Security from the Security sub-menu.
• Enter your Notes password when prompted. A User Security window will open.
• Click on the "+" sign to the left of Identities of Others then select Authorities.
• Open the Certificates drop-down menu then select Internet Root Authorities from it.
• Click in every empty checkbox in the Trust column. Every name in the Certificate Authority Name column should have a checkmark to its left, even if it looks like a duplicate.
• Click OK in the User Security Window. Click Yes when asked "Save changes to your authorities list?"
• A window will open stating "Trust operation succeeded for certificate issued to" followed by information about a specific certificate. Click OK. This will be repeated for each name listed in the Certificate Authority Name column.

http://www.sfsu.edu/~helpdesk/lotus/lotusnotes/lotusfaq/index.htm