From the category archives:

SMTP

Removing internal host names and IP addresses from message headers

May 20, 2008

Another frequently asked question about SMTP mail – how can I remove internal host names and IP addresses from outbound Internet mail? More often than not, this results from the belief that somehow if the outside world finds out an organization’s internal IP addresses and host names, it makes the organization vulnerable. Auditors love to [...]

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Masquerading SMTP Virtual Servers: Changing the fqdn and masquerade domain

December 18, 2007

You can change the fully-qualified domain name (fqdn) used by a SMTP virtual server from its properties | Delivery tab | Advanced | Fully-qualified domain name. In the following example, we change the fqdn of a SMTP virtual server from its default – letter.exchangelabs.net, to postcard.exchangelabs.net. Figure 1: Changing the fully-qualified domain name in SMTP [...]

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Connection Filtering, RBLs and SMTP logs in Exchange 2007/2010

July 27, 2007

Exchange Server 2003′s Connection Filtering feature allows you to block connections from IP addresses explicitly added to the Global Deny List, or drop messages from IP addresses listed on a RBL (Real-Time Blackhole List / Real-Time Block List). Note: The term “RBL” is commonly used to describe DNS Black Lists (DNSBLs), but it’s a trademark [...]

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Address Literals in Exchange 2007 and Exchange 2010

June 21, 2007

RFC 2821 allows the use of a literal form of a recipient’s address, which uses the destination system’s IP address enclosed by square brackets in the domain part, as an alternative to a domain name. Commonly known as address literals, this form of addressing helps in delivery of mail to a recipient when the recipient’s [...]

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Logging SMTP Protocol Activity in Exchange 2010 and Exchange 2007

May 3, 2007

I wrote about SMTP logging in Exchange Server 2003/2000 in what is one of the most popular posts on Exchangepedia [read previous post - "Logging SMTP protocol activity"]. Exchange Server 2007 has its own SMTP stack, and what I like to think of as smarter or more intelligent Receive Connectors (these are protocol listeners, roughly [...]

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Protect users from spam from your own domain in Exchange 2010 and Exchange 2007

May 1, 2007

One of the common complaints from users and many messaging folks is spam received from senders that appear to be from your own domain. SMTP mail is exchanged with anonymous Internet hosts without any authentication. Headers can be and are effortlessly spoofed. Rather than using an unregistered or invalid domain in the From: header, many [...]

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RFC 2821, HELO again: Validating the HELO/EHLO domain

April 19, 2007

RFCs 2821 and 1869 specify the format of HELO/EHLO commands issued by a SMTP client to initiate a SMTP session. RFC 2821 on HELO/EHLO command: 4.1.1.1 Extended HELLO (EHLO) or HELLO (HELO) These commands are used to identify the SMTP client to the SMTP server. The argument field contains the fully-qualified domain name of the [...]

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Exchange Server 2007: Managing And Filtering Anti-Spam Agent Logs

April 17, 2007

Exchange 2007 includes a number of anti-spam agents to filter spam. The anti-spam agents log their actions in (anti-spam) agent logs. The default agent log locations: Exchange 2010: \Exchange Server\V14\TransportRoles\Logs\AgentLog Exchange 2007: \Exchange Server\TransportRoles\Logs\AgentLog Agent Log Configuration You can’t change the agent log location. Here are the available config options: Enable/Disable agent log: On transport [...]

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HOW TO: Send as alternate email address

April 13, 2007

This is one of the more frequently asked questions in different forums – how do I send as an alternate address (aka proxy address or alias)? You can use Exchange Server’s Email Address Policies (Exchange Server 2010/2007) or Recipient Pollicies (Exchange 2003), or the E-mail Addresses tab in EMC (Exchange 2010/2007) or Active Directory Users [...]

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Exchange Server 2007: How to turn off the Back Pressure feature on transport servers

March 29, 2007

In reference to previous post titled “Exchange Server 2007 Transport: 452 4.3.1 Insufficient system resources“, the Back Pressure feature, that detects resource pressure on Exchange Server 2007 transport servers and stops accepting new message submission if low on resources, can be turned off. Here’s how to do it: Open the EdgeTransport.exe.config file from \Exchange Server\bin [...]

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