Plesk(SPF): Setting Up Support for Sender Policy Framework System

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Posted on February 23, 2009

To set up support for Sender Policy Framework on your server:

1. Click the Server shortcut in the navigation pane.
2. Click the Mail icon in the Services group. The server-wide mail preferences screen will open on the Preferences tab.
3. Select the Switch on SPF spam protection check box and specify how to deal with e-mail:
* To accept all incoming messages regardless of SPF check results, select the Create only Received SPF-headers, never block option from the SPF checking mode drop-down box. This option is recommended.
* To accept all incoming messages regardless of SPF check results, even if SPF check failed due to DNS lookup problems, select the In case of DNS lookup problems, generate temporary errors option from the SPF checking mode drop-down box.
* To reject messages from senders who are not authorized to use the domain in question, select the option Reject mail if SPF resolves to fail from the SPF checking mode drop-down box.
* To reject the messages that are most likely from senders who are not authorized to use the domain in question, select the option Reject mail if SPF resolves to softfail from the SPF checking mode drop-down box.
* To reject the messages from senders who cannot be identified by SPF system as authorized or not authorized because the domain has no SPF records published, select the option Reject mail if SPF resolves to neutral from the SPF checking mode drop-down box.
* To reject the messages that do not pass SPF check for any reason (for example, when sender’s domain does not implement SPF and SPF checking returns the “unknown” status), select the option Reject mail if SPF does not resolve to pass from the SPF checking mode drop-down box.
4. To specify additional rules that are applied by the spam filter before the SPF check is actually done by the mail server, type the rules you need in the SPF local rules box.

We recommend that you add a rule for checking messages against the open database of trusted senders, for example, ‘include:spf.trusted-forwarder.org’. For more information on SPF rules, visit http://www.ietf.org/internet-drafts/draft-schlitt-spf-classic-02.txt.
5. To specify the rules that are applied to domains that do not publish SPF records, type the rules into the SPF guess rules box.

Specifying a/24 mx/24 ptr gives good results for spam filters scoring Received-SPF lines.
6. To specify an arbitrary error notice that is returned to the SMTP sender when a message is rejected, type it into the SPF explanation text box.

If no value is specified, the default text will be used as a notification.
7. To complete the setup, click OK.

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