+1 to Ed's advice. All that an iodine dip does is act as an antiseptic, same as iodine with us. It will help heal torn flesh where a bacterial infection may have started, or in general as the coral is stressed from shipping, it becomes more susceptible to bacterial infections. Iodine stops this and keeps the bacteria out of your tank. Esp. important with really fleshy corals; all the LPS fit here, SPS aren't as fleshy but more susceptible to infection.
As an aside, iodine dips are great for corals that have been in the tank too. Overfeeding can result in bacterial infections as the food literally rots in the corals gut. *Sometimes* iodine can help with this. I've seen it help reverse what looked like upcoming death of euphyllia, as they are super susceptible to infection and die quickly from them.
Once again, iodine isn't the cure all nor the only thing to dip with but it's an antiseptic that works well as what it does.