Whilst I get 10/10 for my emails on the tester, I always get an issue with DKIM, but I cannot work out how to resolve it:
mail-tester.com; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=xxxxxxx.co.uk header.i=@xxxxxxx.co.uk header.b=dJ2SOmgB; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=amazonses.com header.i=@amazonses.com header.b=TYxQkD5x; dkim=fail reason="key not found in DNS" (0-bit key; unprotected) header.d=xxxxxxx.co.uk header.i=@xxxxxxx.co.uk header.b=PeexJOoH; dkim-atps=neutral
I am sure that the DNS is setup correctly. Is it an Amazon SES setting?