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Managing Spam Filter False Positives and False Negatives

Background Information

Pacific University protects faculty, staff and student email accounts from unwanted and malicious messages via a spam filter. Google (student accounts) and Outlook (employee accounts) also provide additional protection. These filters take a large number of factors into account to guess whether an email is spam/malicious or not. These factors include the reputation of the “from” email address, the reputation of the server that sent the message, the reputation of sites linked to in the email, keywords in the message, whether or not an attachment or embedded image is present, and the amount of text in the message. The rules utilized by these spam filters are constantly changing (to try to keep up with ever-changing strategies used by spammers) so a message that is not filtered today might be filtered tomorrow, or vice versa.

Depending on the likelihood a message is spam or malicious, a message may be delivered to you but placed in your Junk E-Mail or Spam folder or it may not be delivered to you at all.

Two types of errors with spam filtering can happen:

  • A false positive is when a message that is legitimate is marked as spam and treated accordingly.
  • A false negative is when a message that is spam or malicious is not marked as such.

Dealing With False Positives as a Sender

To reduce the likelihood that the messages you send are incorrectly marked as spam or malicious, do the following:

Dealing With False Positives as a Recipient

The best practice is to periodically review your “Junk Mail” folder (faculty and staff) or “Spam” folder (students) to see if any legitimate messages have ended up there. If you find a legitimate message there you can mark it as such. For faculty and staff right-click (Windows) or control-click (Mac) on a message and choose “Mark as Not Junk” or “Never Block Sender” or “Never Block Sender’s Domain.” In student email, you can open a message and click the “Not spam” button above. For BoxerMail users, adding a person's email address to your Contacts will prevent mail from that person as being marked as spam (unless, according to Google, "we know with high confidence that [the messages] are spam").

You should also review your spam quarantine, either via the daily quarantine report emails you recieve or via the SecureMail web interface, as shown in this article: SecureMail Quarantine. Releasing an email from quarantine, as described in the article, will prevent messages from that sender from being quarantined in the future.

You can also refer senders to the Dealing With False Positives as a Sender section above.

If you are asking people to send you information or files, consider using systems other than email. These systems can give you options and ease of management that email does not. If you are asking for information, you could utilize Qualtrics or Google Forms (using your Pacific University login) to create and send a survey. If you are asking for files, you could use the assignment tool within a Moodle course to collect files. See the Center for Educational Technology and Curricular Innovation’s help pages on creating a Moodle course and creating an assignment. You can also create shared folders in Box and ask people to upload files to them. Consult with the Technology Helpdesk if you would like to learn more about using these tools.

Dealing With False Negatives

The best way to deal with false negatives (messages you receive that were not marked as spam) is to mark them as spam.

For faculty and staff, in Outlook, you can right-click on an email (Windows) or control-click on an email (Mac), go to Junk or Junk Mail and choose to mark the message itself as Junk or choose to block all emails from this sender. Keep in mind that Outlook junk mail filtering only works when Outlook is on (it won’t work, for instance, when you are accessing email via your phone or webmail).

For students, in BoxerMail, you can open a message and use the “Report spam” button (octagon with exclamation mark).

Diligent marking as spam can reduce, but will not remove, the amount of spam you receive.

Related Resources

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