Testing IP restrictions on port 25

How do I send a test e-mail message directly to the external static address of my firewall to see if e-mail is delivered outside the range of the eight IPs?

Digg This!     StumbleUpon     Del.icio.us

RELATED CONTENT Antispam Software and Spam Filtering Problems with email spoofing on SBS 2003 Exchange Insider e-zine Securing your Exchange Server 2007 journaling archives Microsoft Exchange Server security dos and don'ts Troubleshooting Microsoft Exchange Server Event ID error 6009 How can I configure Exchange IMF to allow an IP address or DNS? Tool helps identify inbound Exchange Server email flow issues Configure SMTP relay restrictions in Exchange Server 2003 to stop spam Exchange email sent to a domain using SPF authentication is returned Secure Edge Transport servers using the Security Configuration Wizard Antispam Software and Spam Filtering Research ISA Server and Firewalls for Microsoft Exchange Server Top 5 Exchange mobile tips of 2008 Microsoft Exchange Server security dos and don'ts Windows SBS and Exchange Server security configuration best practices Why Exchange ActiveSync fails with NAT firewalls Deploying ISA Server as a firewall for Exchange Server mobile devices Adjust your firewall to avoid Exchange 2007 Direct Push failures OWA stops working from external network connection Enhance OWA logon security using Microsoft ISA Server Firewall problems with Exchange Server 2007 email attachments How and why to disable certain ESMTP verbs

RELATED GLOSSARY TERMS Terms from Whatis.com − the technology online dictionary greylist  (SearchExchange.com) hash buster  (SearchExchange.com) image spam  (SearchExchange.com) KnujOn  (SearchExchange.com) Sender ID  (SearchExchange.com) spam confidence level  (SearchExchange.com) spamblock  (SearchExchange.com) spim  (SearchExchange.com) tarpitting  (SearchExchange.com) teergrube  (SearchExchange.com)

RELATED RESOURCES 2020software.com, trial software downloads for accounting software, ERP software, CRM software and business software systems Search Bitpipe.com for the latest white papers and business webcasts Whatis.com, the online computer dictionary

The best and simplest way to test this is with a telnet session. Here is an example that you can use to test. Make sure you do this from a machine with an external IP address. Using an internal IP address may not give you the desired results.

--------------------------------------------
Telnet ipaddress 25
Helo
Mail from:name@externaldomain.com
Rcpt to:name@domain.com
Data
This is a relay test
.
Quit
--------------------------------------------

Ipaddress -- is the IP address of the host that your MX record points to. In most cases this is an interface on a firewall that does network address translation (NAT).

name@externaldomain.com -– is any e-mail address you want to use outside your company. For example a hotmail or gmail account.

name@domain.com -- should be a valid address of an e-mail account in you company, probably yourself.

If your firewall is working, then you will not be able to even make the telnet connection on port 25. If you are able to get a connection, and subsequently send the test message, from any IP address other than the eight you specified, then the firewall is not working.