Mail and Photo Transfer to new iMac
I have a late 2013 iMac running El Capitan 10.11.6. I am purchasing a new iMac, however, in order to get a trade-in rebate, I have to bring in the old machine at the same time that I will be purchasing the new one, so the old machine won't be available to transfer the files using a cable.
I need to make sure I can move the mail and photos to the new machine. If I back up this data to iCloud, will it be available to download on the new machine? I'm concerned because the iOS versions aren't compatible and I have lost data before due to incompatibility. (I don't have a lot of experience with iMacs.)
Any tips to avoid losing data would be greatly appreciated!