Our reports right. Have you lodged a ticket?

Hello Christophe, I'm sorry to hear you're having trouble with DKIM. A lot of the time issues verifying the new key can stem from DNS issues. Can I have you try changing your DNS servers in Settings>General to the following, then recheck periodically for a couple of hours to see if it validates?

If you already have these set, you might try issuing an ipconfig /flushdns on the Windows server SmarterMail runs on, then check again. Let me know how it goes!

No worries Christophe, I've seen similar issues in the Windows DNS components in the past, and Windows isn't very detailed about the cause of the error making it more difficult to troubleshoot. Glad to hear you got it resolved though! :-)