Most rabbits will love to eat raisins, however they are really high in sugar and if your rabbit eats too many of them it can cause diarrhea. This is because the natural diet of rabbits is primarily based upon fiber rich hay. The fiber is fermented slowly by good bacteria that produce many of the B-vitamins and other nutrients that rabbits need to stay healthy. If you feed bunnies raisins or other foods that are rich in sugar you'll be feeding the bad bacteria in their digestive system which will then cause them to have digestive troubles.
For this reason rabbits need a high fiber diet that is low in starch and sugar. It is best to fortify the high fiber diet of your rabbit with chelated minerals and balance it with natural vitamins to ensure that their organs continue to function properly. The most common deficiencies are the vitamin choline and the mineral phosphorous which directly impact the health of every cell in your rabbit. This is why it is important to feed your bunny a complete and balanced pelleted diet.
Baby rabbits need quality protein and a high fat diet like "mamma's milk" to support their fast growth. However, they only need this style of a diet until they are teenagers, or around 12 weeks of age. At this point they need to switch to eating an adult formula. Adult rabbits will be far healthier eating a grain-free and soy-free pet rabbit food. They need a continuous supply of specific minerals to maintain health and you'll see a real difference in the quality of their fur coat and overall playfulness if you provide it for them.
So can rabbits eat raisins? Yes, but limit it to a very small snack.