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Trend Micro Email Security allows you to add SPF settings to validate an inbound message comes from the authorized IP address stated in the DNS record for the sender domain within the envelope address.
Note
Note
Trend Micro Email Security provides a built-in default rule that has the lowest priority to ensure you receive a baseline level of protection. The default rule cannot be deleted.
You can create only one single rule for each Managed Domain. The default rule will be applied if no other rules are matched based on the Managed Domain.

Procedure

  1. Go to Inbound Protection → Domain-based Authentication → Sender Policy Framework (SPF).
  2. Click Add.
    The Add SPF Settings screen appears.
  3. Select a specific recipient domain from the Managed domain drop-down list.
  4. Select Enable SPF to enable SPF check in Trend Micro Email Security.
  5. Optionally select Insert an X-Header into email messages to add the SPF check result into the email message's X-Header.
    Trend Micro Email Security adds messages similar to the following in email message's X-Header named X-TM-Received-SPF:
    Status
    X-Header
    Pass
    X-TM-Received-SPF: Pass (domain of example_address@example.com designates 10.64.72.206 as permitted sender) client-ip=10.64.72.206; envelope-from=example_address@example.com; helo=mailserver.example.com
    Fail
    X-TM-Received-SPF: Fail (domain of example_address@example.com does not designates 10.64.72.206 as permitted sender) client-ip=10.64.72.206; envelope-from=example_address@example.com; helo=mailserver.example.com
    SoftFail
    X-TM-Received-SPF: SoftFail (domain of transitioning example_address@example.com discourages use of 10.64.72.206 as permitted sender) client-ip=10.64.72.206; envelope-from=example_address@example.com; helo=mailserver.example.com
    Neutral
    X-TM-Received-SPF: Neutral (10.64.72.206 is neither permitted nor denied by domain of example_address@example.com) client-ip=10.64.72.206; envelope-from=example_address@example.com; helo=mailserver.example.com
    None
    X-TM-Received-SPF: None (domain of example_address@example.com does not designate permitted sender hosts) client-ip=10.64.72.206; envelope-from=example_address@example.com; helo=mailserver.example.com
    PermError
    X-TM-Received-SPF: PermError (domain of example_address@example.com uses mechanism not recognized by this client) client-ip=10.64.72.206; envelope-from=example_address@example.com; helo=mailserver.example.com
    TempError
    X-TM-Received-SPF: TempError (error in processing during lookup of example_address@example.com) client-ip=10.64.72.206; envelope-from=example_address@example.com; helo=mailserver.example.com
    Note
    Note
    If the value of envelope-from is blank, the value of helo will be used instead for the SPF check.
  6. Under Actions, specify the action to take based on the SPF check result and select whether to tag the subject or send a notification for the message that fails SPF check.
  7. Under Tag and Notify, customize the tag and select Do not tag digitally signed messages if necessary.
    Note
    Note
    The Tag subject action may destroy the existing DKIM signatures in email messages, leading to a DKIM verification failure by the downstream mail server. To prevent tags from breaking digital signatures, select Do not tag digitally signed messages.
  8. Under Ignored Peers, do any of the following:
    • To add ignored peers to skip SPF check for a specific sender, specify the sender's domain name, IP address or CIDR block in the text box and click Add.
      Note
      Note
      Trend Micro Email Security will not implement SPF check for email messages from the specific domain, IP address or CIDR block. The email messages will continue to the next step in the regular delivery process.
      However, this does not mean the email messages have passed SPF check. They will fail subsequent DMARC authentication if they do not actually meet specific criteria of the SPF standard.
    • To search for existing ignored peers, type a keyword and click Search.
    • To import ignored peers from a CSV file, click Import.
      The following import options are available:
      • Merge: append the ignored peers to the existing list.
      • Overwrite: replace the existing list with the ignored peers in the file.
    • To export all ignored peers to a CSV file, click Export.
  9. Click Add to finish adding the SPF settings.
    Note
    Note
    All the settings you added take effect only when you click Add.