block external emails from coming in   

This is sort of continuing a previous question, where we have a 2003 exchange 
server which is being sent spam to office@companyname.com.au

what is happening is the spam email is being sent to the above adress, 
however the person sending it is choosing to send it directly to the exchange 
server.

ordinarily, if someone sends an email to office@companyname.com.au, it will 
point to an offsite email server server. The offsite Email server is the 
primary MX record listing.

from there, spam is removed, and it is stored as a normal POP email account 
on that server.

the Exchange server has a POP connector, which collects its emails from the 
offsite Email server, which is where the user then collects their mail from, 
as a domain based account.

when a user sends mail, it goes through the Exchange email server, and sent 
directly to the net.

heres the issue i am having: i need to block emails coming into the exchange 
server from the outside world, while still letting emails be sent and 
received from inside the network, and also still being able to check emails 
via the pop connector to the external server.

i dont have access to the physical router. 

help?

date: Tue, 13 May 2008 21:16:01 -0700   author:   Nick

RE: block external emails from coming in   

Hi
simplest way to do this is to only allow authenticated SMTP sessions at your 
virtual SMTP server.
It probably requires a little config change at all your clients (they have 
to authenticate first) but it works.

Henry

"Nick" wrote:

> This is sort of continuing a previous question, where we have a 2003 exchange 
> server which is being sent spam to office@companyname.com.au
> 
> what is happening is the spam email is being sent to the above adress, 
> however the person sending it is choosing to send it directly to the exchange 
> server.
> 
> ordinarily, if someone sends an email to office@companyname.com.au, it will 
> point to an offsite email server server. The offsite Email server is the 
> primary MX record listing.
> 
> from there, spam is removed, and it is stored as a normal POP email account 
> on that server.
> 
> the Exchange server has a POP connector, which collects its emails from the 
> offsite Email server, which is where the user then collects their mail from, 
> as a domain based account.
> 
> when a user sends mail, it goes through the Exchange email server, and sent 
> directly to the net.
> 
> heres the issue i am having: i need to block emails coming into the exchange 
> server from the outside world, while still letting emails be sent and 
> received from inside the network, and also still being able to check emails 
> via the pop connector to the external server.
> 
> i dont have access to the physical router. 
> 
> help?

date: Wed, 14 May 2008 00:56:01 -0700   author:   Henry

RE: block external emails from coming in   

to clarify: this will mean that any emails sent to the domain the exchange 
server is on (companyname.com.au) wont be accepted unless its also given a 
username and password by the mail server sending to it? note that people 
arent exactly getting into the exchange server from the outside world to 
re-send emails to other addresses, its a mail server that is passing on an 
email to a genuine email address which is located on domain the exchange 
server is sitting on.

if this is right, can you point me in a "how to" to setup the authenticated 
SMTP Sessions?

Thanks

"Henry" wrote:

> Hi
> simplest way to do this is to only allow authenticated SMTP sessions at your 
> virtual SMTP server.
> It probably requires a little config change at all your clients (they have 
> to authenticate first) but it works.
> 
> Henry
> 
> "Nick" wrote:
> 
> > This is sort of continuing a previous question, where we have a 2003 exchange 
> > server which is being sent spam to office@companyname.com.au
> > 
> > what is happening is the spam email is being sent to the above adress, 
> > however the person sending it is choosing to send it directly to the exchange 
> > server.
> > 
> > ordinarily, if someone sends an email to office@companyname.com.au, it will 
> > point to an offsite email server server. The offsite Email server is the 
> > primary MX record listing.
> > 
> > from there, spam is removed, and it is stored as a normal POP email account 
> > on that server.
> > 
> > the Exchange server has a POP connector, which collects its emails from the 
> > offsite Email server, which is where the user then collects their mail from, 
> > as a domain based account.
> > 
> > when a user sends mail, it goes through the Exchange email server, and sent 
> > directly to the net.
> > 
> > heres the issue i am having: i need to block emails coming into the exchange 
> > server from the outside world, while still letting emails be sent and 
> > received from inside the network, and also still being able to check emails 
> > via the pop connector to the external server.
> > 
> > i dont have access to the physical router. 
> > 
> > help?

date: Wed, 14 May 2008 16:38:06 -0700   author:   Nick

RE: block external emails from coming in   

you told us three things
a) mail from outside is sent to a mail hoster for anti-spam and then pulled 
down to your exchange server by a pop connector
b) your clients send mail outbound via Exchange (you did not mention whether 
MAPI or SMTP ?) 
c) you get lots of SPAM sent to your Exchange directly from the internet

if this is correct, then only allow authenticated SMTP sessions because
a) the pop connector is not affected
b) MAPI clients are not affected (i.e. internal Outlook or OutlookAnywhere)
c) POP3 or IMAP4 clients are affected (i.e. Outlook Express) but these 
clients can be reconfigured for SMTP authentication
d) nobody can send spam to your Exchange server because authentication is 
required

so far so good
how to enable authentication in POP3 or IMAP4 clients depends on software in 
use
if you use Outlook Express (or Windows Mail if you have Vista) go to 
"Accounts", choose your Mail Account settings, select the server tab
end there check "Server requires Authentication"

for setting  the requirement for authentication at the virtual SMTP server 
select the "Access" tab
click the button "Authentication" and clear the check box for anonymous 
access.

Henry


"Nick" wrote:

> to clarify: this will mean that any emails sent to the domain the exchange 
> server is on (companyname.com.au) wont be accepted unless its also given a 
> username and password by the mail server sending to it? note that people 
> arent exactly getting into the exchange server from the outside world to 
> re-send emails to other addresses, its a mail server that is passing on an 
> email to a genuine email address which is located on domain the exchange 
> server is sitting on.
> 
> if this is right, can you point me in a "how to" to setup the authenticated 
> SMTP Sessions?
> 
> Thanks
> 
> "Henry" wrote:
> 
> > Hi
> > simplest way to do this is to only allow authenticated SMTP sessions at your 
> > virtual SMTP server.
> > It probably requires a little config change at all your clients (they have 
> > to authenticate first) but it works.
> > 
> > Henry
> > 
> > "Nick" wrote:
> > 
> > > This is sort of continuing a previous question, where we have a 2003 exchange 
> > > server which is being sent spam to office@companyname.com.au
> > > 
> > > what is happening is the spam email is being sent to the above adress, 
> > > however the person sending it is choosing to send it directly to the exchange 
> > > server.
> > > 
> > > ordinarily, if someone sends an email to office@companyname.com.au, it will 
> > > point to an offsite email server server. The offsite Email server is the 
> > > primary MX record listing.
> > > 
> > > from there, spam is removed, and it is stored as a normal POP email account 
> > > on that server.
> > > 
> > > the Exchange server has a POP connector, which collects its emails from the 
> > > offsite Email server, which is where the user then collects their mail from, 
> > > as a domain based account.
> > > 
> > > when a user sends mail, it goes through the Exchange email server, and sent 
> > > directly to the net.
> > > 
> > > heres the issue i am having: i need to block emails coming into the exchange 
> > > server from the outside world, while still letting emails be sent and 
> > > received from inside the network, and also still being able to check emails 
> > > via the pop connector to the external server.
> > > 
> > > i dont have access to the physical router. 
> > > 
> > > help?

date: Thu, 15 May 2008 00:15:00 -0700   author:   Henry