American Standard Version (ASV):
So the posts that rode upon swift steeds that were used in the king’s service went out, being hastened and pressed on by the king’s commandment; and the decree was given out in Shushan the palace.
King James Version (KJV):
[So] the posts that rode upon mules [and] camels went out, being hastened and pressed on by the king’s commandment. And the decree was given at Shushan the palace.