Email Security Basics: Anti-Spam, SPF, DKIM and DMARC Explained

Email remains the most common starting point for cyber attacks. A layered email security setup does two jobs: it keeps malicious mail out of your users’ inboxes, and it stops criminals from sending convincing email that appears to come from your domain.

Inbound protection

• Reputation filtering blocks mail from known bad senders.
• Content and attachment scanning detects malware, malicious links and suspicious file types.
• Impersonation detection flags lookalike domains and display-name spoofing of executives.
• Quarantine lets users or admins review borderline messages safely.

Protecting your own domain

• SPF lists which servers may send mail for your domain.
• DKIM adds a cryptographic signature proving the message was not altered.
• DMARC tells receivers what to do when SPF or DKIM fail, and sends you reports.

Start DMARC in monitoring mode (p=none), review reports to find every legitimate sender, then move to quarantine and finally reject. Major mailbox providers now expect bulk senders to have these records in place.

Outbound hygiene

For ISPs and hosting providers, filtering outbound mail prevents compromised accounts from getting your servers blacklisted.

Ubixe Infotech deploys anti-spam gateways and email authentication. Learn about our Anti Spam service or request an email security review.