most organizations have to deal with the
problem of unsolicited email it's very
common for an organization to perhaps
put their own email gateway where all
the information coming in and out is
filtered through that gateway before
ever coming into an internal email
server some organizations will not have
this in their DMZ
they'll instead have that email gateway
in the cloud but it will still perform
checking for spam and make sure that the
data coming through is really intended
for recipients on the inside of your
network this email gateway allows you to
examine all of the communication both
inbound and outbound of your network you
can identify when unsolicited spam
advertisements are being emailed inbound
and if this inbound email appears to be
a phishing attempt you can block it at
the gateway or modify the link before it
arrives into the recipients inbox it's
very common to include antivirus on
these email gateways so that all of the
inbound and outbound attachments can be
scanned and it's also common to include
data loss prevention on the email server
that way if somebody's sending or
receiving an email that contains
personal or proprietary information it
can be filtered out of the email at the
gateway these email gateways use a
number of different methods to identify
unsolicited messages or spam one of
these is to only allow messages from
known good locations this is white
listing everything else would be blocked
except for very specific emails that you
allow another type of spam check is to
see if these messages are conforming to
specific SMTP standards and anything
that doesn't follow the RFC is not
allowed into the network another good
spam check is to perform a reverse DNS
you can examine the inbound email and
who is sending the email message and
then you can examine the IP address of
where that message was sent from you can
then perform a reverse DNS on the domain
name of the sender and make sure that
the email address that originally sent
the email matches what's in the DNS for
that email server if those two IP
addresses don't match then you probably
have some spam and you can discard that
email at the gateway another way to look
for spam is to implement tar pitting on
your email gateway the
is when you slow down the conversation
between your email gateway and the
sending email gateway spammers don't
like to be slowed down they like to send
as many emails as possible and if your
email gateway is slowing down the
conversation the idea is that they will
eventually give up and not send any spam
at all and lastly and perhaps most
obviously there's recipient filtering if
there's inbound email that's being sent
to an email address that's not valid in
your organization you can block it right
at the email gateway as our emails are
traversing through the internet it
becomes very easy for a third party to
view that information and many times the
mail that we're sending is all in the
clear it's not encrypted if you're
sending and receiving sensitive
information it's practically a
requirement that this information be
encrypted in the email message the
challenge that we have is the encryption
process for most email systems is not
one that's seamless or automatic and
there are a number of steps you have to
go through just to make sure your email
message will be encrypted the email
gateway is a great place to check to see
if the outbound emails are properly
encrypted you can check for a certain
type of traffic or traffic from a
particular email address and make sure
that a policy applies to encrypt that
data some email gateways can even send a
text message to the recipient of the
email letting them know what the
password is so that when they receive
the email they'll be able to decrypt the
data and if your email client already
includes an encryption process the
Gateway can recognize that encryption
and allow that email to be sent normally
you