This person is a scammer claiming to sell pets at no cost to you. Basically trying to get you to pay upfront for shipping for a  puppy and offering a great deal for a designer pet. They may email you something like this:

Hello Hello,
This is Grace again. thanks so much for the interest regarding the
puppies they  have very good temperament with kids and other pets,very
playful, This cuties can’t wait to meet you and join your
family!! Roy and Mercy are very gentle and fun Pomsky puppies Mother
was a Pomeranian while father was a Husky   I offer my puppies
alongside a set of Custom Bed, Harness/leash, bowl set, crate/crate
pad,food samples,2 piddle pads (being piddle pad trained),and toys
since i will not be keeping the puppies any more..About the puppies, a
male and a female available.
-Age:10 weeks 4days old
-Both puppies are not fixed.
-Sociability:love to play especially with kids,their toys and other dogs.
-Potty trained,already on regular exercises as i usually take them for a walk.
-Vaccinated up-to-date, wormed and veterinary tested.

-Potential:Perfect temperament,no worries with house noises and other pets.
The reason i am looking for a forever home for these puppies is
because i have Alzheimer and my doctor has strongly advised me for
medication. I am so so sorry to tell you all these but i think i
should be honest with you. I need regular prevention and for this
reason,i have moved to 4372 E Modoc Drive phoenix,  AZ 85044 closer to
my doctor for medication. So i want to give out the puppies to a
loving and caring home and concentrate on my health. I shall be
responsible for the shipping arrangement and its going to cost you
$400 for each puppy to be shipped over to your address if you can't
pick up the puppies at my address . Looking for a caring home for
these puppies has always been my wish,so i have some few question for
you if you don't mind answering them.
-Are you a breeder or do you intend to breed the puppy when they come over?
-Do you have a vet hospital around your location?
-Do you have kids or pets loving home?
-Where exactly are you located  & what's ur zip code?
-Is there some one to take care of the puppy if you are not around?

Please do let me know  if you are interested in male of female
Thanks

I kind of messed around with the person a bit, they will go to great lengths to answer your questions etc. All lies anyways.