Anti-Spam

Telling Exchange about (non-Exchange) SMTP servers

For anti-spam agents like IP Block List providers (aka DNSBLs/RBLs), and Sender ID, it is important to know about which non-Exchange SMTP servers receive inbound internet mail. This allows it to ignore the SMTP servers that belong to your organization when parsing headers (in topologies where the Edge server – or the Hub Transport server […]

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Exchange Server 2007 exposes SCL in message headers

Exchange Server 2003’s Intelligent Message Filter (IMF) assigns a SCL— a value that indicates the probability of a message being spam – to every message it scans. SCL is assigned based on factors such as message content, headers, and IP addresses. By default, Exchange Server and Microsoft Outlook do not expose this SCL value assigned […]

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Turning on Recipient Validation in Exchange Server 2007

The Edge Transport server role in Exchange Server 2007 performs messaging hygiene functions such as Connection Filtering, Sender & Recipient Filtering, Content Filtering, and SenderID Filtering. (You can also install antispam agents on the Hub Transport server role— for topologies without an Edge server. See ‘HOW TO: Install anti-spam agents on Hub Transport server‘.) In […]

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Texas spammer turns “antispam-activist” after million dollar settlement

In an interesting twist, Texas spammer Rylak Pitylak – listed as the world’s 4th “most prolific spammer” by Spamhaus – has turned over a new leaf and now refers to himself as an “antispam activist”. This epiphany happened after coughing up a million dollars in a settlement with Microsoft and the state of Texas, according […]

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IMF: Archiving spam

As explained in previous posts, the Intelligent Message Filter (IMF) offers a few configuration options. The primary interface for configuring IMF is under Global Settings | Message Delivery properties | Intelligent Message Filtering tab. Figure 1: IMF configuration options in Global Settings | Message Delivery | Properties | Intelligent Message Filtering tab Here you specify […]

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Exchange Server 2003 SP2, using SenderID? You need this hotfix!

If you’ve just upgraded to Exchange Server 2003 Service Pack 2 and have enabled Sender ID filtering, you need to apply a hotfix to prevent the server from stopping to respond. According to the KBA, the problem occurs because of a race condition caused by the SMTP protocol. A race condition occurs when a device […]

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Exporting Sender Filter List

Messages from specific senders can be blocked by implementing sender filtering. Blocked senders are specified in Global Settings Message Delivery properties Sender Filtering tab (see screenshot). The Senders list is saved in the msExchTurfListNames attribute of the Default Message Filter object. It is a multi-valued attribute. It can be exported using ldifde/csvde if you take […]

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Exchange Server 2003 SP2 and IMF

Before you install Exchange Server 2003 SP2 you need to uninstall Intelligent Message Filter (IMF). When you do this, the settings from the SMTP virtual server where you allowed filtering are also removed. After SP installation if you go to Intelligent Message Filtering settings (Global Settings -> Message Delivery -> Properties -> Intelligent Message Filtering […]

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Exchange SP2 – Connection Filtering that actually works

I was excited to find out about Connection Filtering (screenshot) in Exchange 2003 – finally I could use RBLs (real-time block lists) without having to dabble with event sinks!! (This is from back in the days when RBLs were still sexy and could keep a good chunk of spam away from your users… ) Connection […]

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