is EZpost.biz a legit. advertizing company. They offer to sell my RV
for $149 until sold or money back after 6 months.
Is this a scam?

The company is not registered with the Oklahoma Secretary of State,
the mailing address of the domain owner is different from the
company's address ... and the website is horribly cheap and shabby. It
cries "I'm a scam!"

Scriptor

The address listed as the company's headquarters is "200 N. Oak Ave.,
Broken Arrow, OK 74012."

I used to live in Broken Arrow, Oklahoma. I do not believe such an
address exists. While there is an Oak Avenue, it is South, not North,
and the addresses on it have four digits, not three.

The US Post Office (usps.com) shows this as a legitimate address:

200 N OAK AVE
BROKEN ARROW OK  74012-8348

Obviously, this doesn't make it a legitimate business, just a legitimate address.

I retract my comment. It's been a while since I lived in Broken Arrow.
If the USPS says it's a real address, then it is.

I have a used boat sales business.  I recently received two queries on
my boats that seemed unreal to my business email from addresses at
fastmail.fm and mm.st.  Both domains are owned by the New York
Internet Company, belong to the same subnet, and the subnet is
registered to fastmail.fm.  Fastmail.fm is based in Parkville,
Victoria, Australia.  Then I suspiciously received three notes from
EZpost with a hotmail source address (not an EZpost.com, which one
would expect), all three sent to "sides777@fastmail.fm", with my name,
plus many others, in the CC list.  Incidently, "TJSIDES@fastmail.fm"
was the source email of one of the phony queries.   The network
address is at 66.111.4.0/24, and you may explore this at
www.arin.net/whois, if you choose to make a squawk about it.
This spells SCAM SCAM SCAM!!!  DO NOT SEND THEM MONEY!!!!