Certain fragrance and essential oils we sell are flammable under very specific conditions. This is called the flashpoint and is the point at which the oil may ignite if held to a flame.
The flashpoint will dictate how a particular oil can ship.
141 Degrees and below: Low Flashpoint - Will ship Ground Only and cannot be shipping via Air, 2nd Day Air, or Internationally
142-199 Degrees: Medium Flashpoint - Will ship UPS Only and cannot ship via the USPS Postal
200 Degrees or above: High Flashpoint - No shipping restrictions
If you are not seeing shipping options when you check out, look at the flashpoint of the individual oils in your cart - most likely there is a restricted item in there.