When opening messages in a Notes mail file, the following error message appears:
“Illegal circular USE: CoreEmailClasses”
The “Illegal circular USE” message will appear when the script library CoreEmailClasses is missing in the mail file.
Replace the design of the mail file with the appropriate mail template to restore the script library.
To check if the script library is available, open the mail file in Domino Designer, expand Resources, then the Script Libraries. The library CoreEmailClasses should be listed.
In one case, replacing the design of the mail file did not resolve the issue. Instead, the customer had to first delete the memo form stored in the mail file and then replace the design.