{"id":3926,"date":"2024-08-02T06:24:06","date_gmt":"2024-08-02T06:24:06","guid":{"rendered":"https:\/\/www.warmy.io\/blog\/how-to-set-up-postmark-spf-dkim-dmarc\/"},"modified":"2026-06-14T21:09:44","modified_gmt":"2026-06-14T21:09:44","slug":"how-to-set-up-postmark-spf-dkim-dmarc","status":"publish","type":"post","link":"https:\/\/www.warmy.io\/blog\/how-to-set-up-postmark-spf-dkim-dmarc\/","title":{"rendered":"Postmark’s Email Security: SPF, DKIM, and DMARC [Setup Explained]"},"content":{"rendered":"\n

SPF, DKIM, and DMARC are the three email authentication protocols every sender must configure to reach the inbox. SPF authorizes which servers can send on your domain’s behalf, DKIM signs each email with a cryptographic key, and DMARC enforces policy when either check fails. Together they protect your domain from spoofing, satisfy Gmail and Outlook’s mandatory bulk sender requirements, and directly improve inbox placement.<\/p>\n\n\n\n

Cybercriminals send an estimated 3.4 billion phishing emails daily<\/a> worldwide. SPF, DKIM, and DMARC stop spoofed email from reaching your recipients’ inboxes \u2014 and they now determine whether your own legitimate email reaches the inbox at all. Google required these protocols for bulk senders from February 2024 with full enforcement from November 2025, and Microsoft followed with identical requirements for Outlook, Hotmail, and Live.com from May 5, 2025<\/a>. Non-compliant senders now face permanent 550 rejections. This guide walks you through setting up all three with Postmark.<\/p>\n\n\n\n

\"pastmark\"<\/figure>\n\n\n\n

SPF vs DKIM vs DMARC: How They Work Together<\/h2>\n\n\n\n

All three protocols serve different purposes and must be configured together. For a deeper look at why each one matters for deliverability, see why you need to configure SPF, DKIM, and DMARC<\/a>.<\/p>\n\n\n\n

Protocol<\/strong><\/th>What It Does<\/strong><\/th>What It Protects Against<\/strong><\/th>Required in 2026<\/strong><\/th><\/tr><\/thead>
SPF<\/td>Lists authorized mail servers for your domain in DNS<\/td>Unauthorized servers sending as your domain<\/td>Yes \u2014 Gmail & Outlook require both SPF and DKIM<\/td><\/tr>
DKIM<\/td>Adds a cryptographic signature to every outbound email<\/td>Content tampering in transit<\/td>Yes \u2014 Gmail & Outlook require both SPF and DKIM<\/td><\/tr>
DMARC<\/td>Enforces policy when SPF or DKIM fails; aligns the visible From address<\/td>Domain spoofing in the From header; phishing<\/td>Yes \u2014 minimum p=none; p=quarantine\/reject recommended<\/td><\/tr>
BIMI<\/td>Displays your brand logo next to emails in supported inboxes<\/td>Brand impersonation; improves inbox trust<\/td>Optional \u2014 requires VMC or CMC for Gmail and Apple Mail<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Understanding SPF (Sender Policy Framework)<\/h2>\n\n\n\n

What Is SPF and Why It Matters for Email Deliverability<\/h3>\n\n\n\n

Sender Policy Framework (SPF) acts as an authorized sender list for your email domain. You publish an SPF record in DNS that specifies which mail servers have permission to send email on your behalf. When a receiving server gets an email from you, it checks your SPF record and compares the sending IP against your approved list. A match passes; a mismatch fails \u2014 and depending on your DMARC policy, a failure can mean spam routing or outright rejection.<\/p>\n\n\n\n

SPF protects your domain reputation, deters spoofing, and is a mandatory component of Gmail’s and Outlook’s bulk sender requirements.<\/p>\n\n\n\n

Setting Up SPF with Postmark<\/h3>\n\n\n\n

Step-by-step:<\/strong><\/p>\n\n\n\n

    \n
  1. Log into your DNS provider’s control panel.<\/li>\n\n\n\n
  2. Create a new TXT record for your domain with the hostname @<\/strong> (your root domain).<\/li>\n\n\n\n
  3. Set the value to: v=spf1 include:spf.mtasv.net ~all<\/strong> \u2014 this authorizes Postmark’s servers to send on behalf of your domain. If you use other email services alongside Postmark, add their include: entries to the same record before the ~all qualifier.<\/li>\n\n\n\n
  4. Save the record and allow up to 48 hours for DNS propagation. For context on why propagation sometimes takes longer than expected, see this guide on how DNS propagation delays affect email deliverability<\/a>.<\/li>\n\n\n\n
  5. Verify your record with Warmy’s Free SPF Record Generator<\/a> \u2014 it validates syntax and confirms you’re within the 10-lookup limit.<\/li>\n<\/ol>\n\n\n\n
    \"SPF<\/figure>\n\n\n\n

    Common pitfalls \u2014 and how to avoid them:<\/strong><\/p>\n\n\n\n