56CHAPTER 4: ANTI-SPAM CONFIGURATION
Message Envelope Parameters
These parameters will not be visible to the user. They are the “handshake” part of the SMTP protocol. You will need to look for these in the transport logs or have other knowledge of them.
■<<Mail Envelope>> — This parameter allows for a match on any part of the message envelope which includes the HELO, Client IP and Client Host.
■HELO — This field is easily faked and is not recommended for use in spam control. It may be useful in whitelisting a source of mail. Example: mail.example.com.
■Client IP — This field will be accurately reported and may be reliably used for both blacklisting and whitelisting. It is the IP address of the system initiating the SMTP connection. Example: 174.17.19.241.
■Client Host — This field will be accurately reported and may be reliably used for both blacklisting and whitelisting. Example: mail.example.com.
The following envelope parameters (Envelope Addr, Envelope To and Envelope From) may be visible if your client supports reading the message source. They can also be found in the transport logs. Other header fields may be visible as supported by the mail client.
■Envelope Addr — This matches on either the Envelope To or Envelope From. These fields are easily faked and are not recommended for use in spam control. They may be useful in whitelisting a source of mail.
Example: user@example.com.
■Envelope To — This field is easily faked, and is not recommended for use in spam control. It may be useful in whitelisting a source of mail. Example: user@example.com.
■Envelope From — This field is easily faked, and is not recommended for use in spam control. It may be useful in whitelisting a source of mail. Example: user@example.com.
