Yes. Never trust what agents tell you. They will sometimes lie and without checking say that it's a blackout date on KE, when it is not.

I always keep a text file handy of the actual blackout dates as per the fare rules.

Here I have just reformatted to made it more clear (i.e. put in the line breaks, so it's not all jumbled together and harder to read, which is how DL presents it).

It's easy to get it. Just go to delta.com, search for any int'l award ticket, before booking click on the fare rules link, copy and paste and save the BLACKOUT DATES section.

It is published and easy for anyone to see, you just have to make a dummy award int'l booking, prefereably with a non-DL flight in it, to ensure that the BLACKOUT DATES section will be properly populated (as opposed to say NONE as it would for domestic, DL only).