It is only by having your feelings hurt that you can achieve true spiritual greatness. When you are feeling hurt you have a choice of two directions in which to go. You can indulge yourself in self-pity for the pain you feel, or you can rise above it and realize that in the greater scope of things the pain is meaningless.
King David did not achieve his greatness until after he was ruthlessly persecuted by his enemies. Mordechai and Esther were viciously attacked by their fellow Jews and blamed for the decree of Haman. It was only following those attacks that they too achieved greatness. The humility demonstrated by not reacting negatively creates a great spiritual aura around the person. The fight against disliking others is the most significant challenge in the life of each and every person. It is altogether too easy to dislike one person one day, and then another the next. After 120 years you will discover that all the efforts you devoted to Torah study, prayer and other good deeds, do not even begin to approach the value of creating a peaceful atmosphere and friendship amongst people.

The primary goal of Purim is to reunite with people and put aside differences. The sending of Mishloach Manos is in order to create friendship and brotherhood with others. It is this power of Purim that leads the Zohar to teach us that Purim and Yom Kippur share a connection. When one is able to overcome his hurt he creates a spiritual connection with the divine. He rises above his base humanity and physical existence and rises to a higher plane. This is similar to the activity of the Kohen Gadol (High Priest) on Yom Kippur. It is the only day of the year in which he enters the Holy of Holies. The Holy of Holies is the place where heaven touches earth. Where the finite and infinite meet.

The High Priest can only get there once a year. But we have the ability to get there every day. Especially on Purim.