Make sure that you are using a supported Notes 7 Client.
Ensure that your full Notes Address is listed as the owner of the mail file.
Open the Notes.ini file (Normally found in C:\Notes\data)
Press CTRL and F to search for the phrase OEMClient
IF the value associated with the OEMClient variable is set to 1 THEN delete the entire line from the file, save and close, then restart Notes.
IF the value associated with the OEMClient variable is set to 0 or if it does not exist in the notes.ini file THEN go to step 4.
Replace the design of the mail file.