About 15 years ago, I found that I could
send email directly between my OpenVMS home system
and work computers.  [I didn't have to set up anything.  It just worked.]  [Not a server per se (to, say, PCs
with email clients); just using the built-in
mail program to send and receive mail.]
Then, it stopped working.  It turns out that Verizon (for DSL, at
least), started reporting/registering
all of the DHCP IP addresses that they
would assign to home users as SPAM sources, so they'd
be blocked everywhere.  You had to pay for business-class service
(and get a static address) for
them to let things through.
Verizon also blocked port 80 inbound.  [Easy to get around; I just started using a
different port.]
{Verizon was a nightmare in general.  They collected the money that they pretended
on the bills
is a tax, even though it's a fee that
Verizon keeps, purportedly for maintaining copper lines, and
actually spent the money on cell phone
infrastructure.  [There were lawsuits
against Verizon in
several states for fraud; In 
dreadful service.  [I started running curl in a script to log
all of the outages.  And, I often managed
to get no more than 32K baud.  When it rained, the baud rate often dropped
below 1K.  I was paying
for 1M - 3M.]}
Then, some volunteers in my town arranged
for the local municipal light department to run optical
fiber cable through the town.  We now have Spectrum, and, as far as I can
tell, nothing is blocked.
[And, the modem presents a real internet
address to the house/Ethernet side.  -I
have a separate
router, separate WiFi access point...]  Haven't tried sending email directly in a
while, though.
From: Mike Peckar via
WLUG [mailto:wlug@lists.wlug.org] 
Subject: [WLUG] opinions on home
email services