When I send an email the following error message is displayed: "One of your filters uses a custom header that contains an invalid character, such as ':', a non-printable character, a non-ascii character, or an eight-bit ascii character. Please edit the msgFilterRules.dat file, which contains your filters, to remove invalid characters from your custom headers." This is followed by a message saying that the email has been sent and saved despite the error. The problem happened after transferring to Windows 10 (from Win 7) I have deleted ALL msgFilterRules.dat files and ALL filters, but the message persist. Any suggestions on what else to try? Thanks, Ben