delete unsent message

Delete unsent message, - but from where?

If you have not checked “send immediately” there is a folder called “outbox” that you can show under smart folders. In that folder a mail remains until the next sync occurs. From there it can be deleted.

I had clicked “Send” (I do not have a send immediately button), but I get the repeated (over 4 days every 5 minutes)  error message "[IMAP] - Unable to upload message “Video Yesterday” to folder Trash ([LIMIT}Append Command exceeds the  maximum allowed size)

I have no idea about the error message, but what I meant with “send immediately” is an option in Settings-Mail-Send: “send messages immediately” if unchecked, mails will be send on next sync instead of at once

Hello John,
please copy the full error message and also the content of the Tools>Operations>Log window when this error pops up.