How your email server works

http://www.imacmailer.com This video shows how a standard SMTP server works. It is a detailed video showing what happens when you hit send button on your mail client.

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Closed Caption:

hi in this video I'm going to show you
how your email server works
it's going to demystify the process
behind
what's going on when you push the Sun
button on your mail client and how your
message is delivered to your intended
recipient
let's take a moment and dive in let's
talk about components of sending and
receiving email whenever you send the
message
and while it is in transit each message
will go through many points very
simplistically they are divided to send
their workstation
this is your own computer where your
mail client is installed
this is the start . once you press some
button
this is where your message is coming
from smtp server and the email must
always come through one
or usually two or three smtp servers
they are sometimes called mail servers
or email service whatever you prefer
will not get stuck on the names but just
so you know
email message storage this is where your
message will end up after you send it
and it is delivered
this is similar to a database of all
messages that are waiting for a
particular user in your case your
message will wait for your recipient to
read it
keep in mind that messages and never
sent directly to your recipients
computer recipient . he checks his mail
store to see if there any messages
waiting for him
and of course your receiver workstation
this is where your recipients computer
and where your message ends up
this is where your recipient will read
it
well let me show you real life scenario
step by step
this is Jane she wants to tell john how
she liked her date with him and she
wants to thank him and invite him to
dinner in a romantic restaurant
she's asking him what was in he prefers
if you like French restaurant downtown
or that lovely small family restaurant
down the street
yeah okay I was talking about the
centerpiece servers
ok let's concentrate so after Jane wrote
this nice message and hit Send waiting
in anticipation
this message is going to her smtp server
every user has one even if you use a
free gmail account or Yahoo or you have
outlook installed
I don't care you will always always send
your message to us and tip your server
this is some people server is a pretty
complex program it will look at the
message
Heather's examine the destination and
we'll try to find the address of another
smtp server that is responsible for
holding messages for John
now here is that other smtp server
of course if both John and Jane have
email accounts on the same domain for
example john's email is john @ gmail.com
and Jane email is Jane @ gmail.com
there's no need to search and of course
there will be no need to contact another
some TP server
this is what is called local delivery
it's similar to send in a letter to a
resident of the same building
you can just go downstairs yourself and
put the envelope into his mailbox
see there's nothing to it now in a more
complex case where John's e-mail is
located elsewhere on another computer
we need to find out where exactly this
is where we asked our dns server to give
us exact location
IP others for those who know the
announce has a huge database of all
network addresses and their arty numbers
and it will quickly search through those
and give us an answer
this is very similar to regular mail
sortation plant
so here's how it goes we already know
John's e-mail is not on gmail for the
same example let's say his email is john
@ yahoo.com smtp server will take away
John ad and we'll be left with yahoo.com
it will down around a special search in
dns email dns records have different
record type it's called MX or mail
exchange for short
it will give it back one or more IP
addresses of the destination servers
yeah there could be more than one
especially for big providers like yahoo
and gmail that process millions of
emails the second but we won't get into
that i just mentioned it to scare you
that's all
from glad that stage is over now we're
almost at the end phase and we know the
destination address
all we have to do is deliver this
message to its destination
our sin city centre will connect to the
destination address which were original
the two servers we'll chat a bit and our
sin T P will hand over the message to
the destination server where Jones has
his mailbox but that is not the end
now John several will check if this
message is spun because you never know
and this stage is so complex have a lot
of and scare you
you will see just the general overview
of this process later and i will
probably have a separate video explained
in what are the most typical and this
part fields are some now I know how they
work
it's important to know if you want to
sound a lot of email for your email
marketing but if you're just out of
curiosity open in this video we don't
need it
just so you know most of your service
processing power is devoted to figuring
if a certain message is spam or not
often there are separate computers just
for that because the river in the
message is pretty easy determine if it's
pump or not is very hard at this point
we're past the power filter and James
message is safely stored in John's
mailbox or should I say in his mail
message store it is waiting for john to
connect to his server and get his
message over to his client
so John can read a lovely letter from
Jane so they can finally pick the
restaurant they both love
so what is smtp why is it called the
smtp what is behind these letters sent
to pee is just an abbreviation for
simple mail transfer protocol
I don't know what so simple about it or
maybe there is some complex mail
transfer protocol somewhere but no
that's the only protocol for email we
have when it was defined by can and
nineteen eighty-two by a special
committee of total brainiacs
they probably thought it was simple but
during that time there was no skype
no instant chart not even email they
used to actually deliver mail by hand
you know one is where it actually
involves the postman
ok
but the protocol itself is text only
back in the day the brainiacs thought
the text is all we will ever need to
deliver
so the protocol is all texts so these
days to deliver pictures and files and
videos other brainiacs on top of the
previous brainiacs created extensions to
this protocol that work around the work
around that was created to work around
sending texts
yeah right okay back to the subject
this protocol is a standard for every
single email server on the planet
so all email in the world is delivered
this way
which means of course that all the
servers on the planet must work this way
and they must adhere to the protocol of
course there's six close Microsoft
because they have special engineers and
they know much better how their mail
server should work in their infinite
wisdom they kind of sort of the support
SMTP protocol but they kind of sort of
don't
well it's very flaky I have seen many
places where they just did something
against the protocol
just because they're microsoft and there
are a gazillion people using their
product they just ignore it but other
than that all others and here to it and
use it
so now we go to actually see a real live
demonstration of a some tea protocol in
action
remember it's a text protocol so all you
will see is text if you were sleeping
before
wake up
this is what's going to happen when you
actually connect to the server
first you are greeted with this error
code 220 means everything's okay
all the error codes let's start with two
means everything is okay and then the
free tags greeting
what you respond to that is usually you
say hello
well in this case I will say extended
hello
and then i will say Who I am
the server will respond with an extended
list of features
these are extensions i was talking about
that are workarounds around the
workarounds
so in this case it will support start
TLS which is encrypted email chunking a
bit moments on all the buzz words you
don't need to know about
now in order for me to send them an
email right now i will go ahead and say
who is this email coming from Yale from
let's say
it says yeah okay
250 remember the error codes with two
are everything is okay
others accepted now i need to say who do
i need to send it to you
and this is accepted
now in email it's all free form so i can
definitely have the same from address
and the same to others
doesn't matter obviously some
spot-checks will filter it out later but
for the sake of demonstration it's okay
and now the main part where the message
comes
I just say data and it says yeah
ok I'm ready to receive your data start
by inputting your data and finish it by
just the dot on a single line
so this data first of all you need to
transmit the headers obviously so the
message will have something like subject
tests and the the message will have I
don't know a date
and that's about it
you can just and a mentor the empty line
ééé empty lion says that here the
Heather's finish and then the message
begins
and to finish this message I just need
to put the dog on a single line just
exactly the same way as this case s and
that's it the messages accept that then
will be routed spot checks very high
level of real
every message that comes into an email
Sarah and even before the message itself
comes the connection it comes from his
suspect email server examines your IP to
see if you're from what is called bad
neighborhood
there are lots of databases that check
and update at least of bad IP addresses
and if your IP will be there
your connection will simply be rejected
before you even have a chance to start
the conversation
it is similar to a saying we don't open
the door to a stranger after your past
that check your server will verify the
headers
you're sending are correct it may check
that a domain from which you claim to
send the message taxes and that is
registered to send email from this AP
then it may also check that the return
address from your AP corresponds back to
the hostname you claim to be from of
course it will check your message itself
as well if you get to that stage
this is what takes the most time there
are special
artificial intelligence filters that are
trained to recognize sperm in your
messages
it will also look for some stop words
such as free make more money and so on
the kinds of words and phrases you will
often find in a spam message
i should say that statistically about
eighty to ninety percent of all emails
in the world right now is spun he has
spiders create most of the heavy
overhead on the system that we use the
end users must pay for it
we pay the fees to our isp
is be invested into heavier
infrastructure and lots of filters just
to be able to accept and then
immediately throw away
ninety percent of all emails of course
this list is by no means a complete list
and i will have to create just a
separate video to expand on the subject
yeah