The short answer is: it depends, but increasingly, yes. For years, DMARC was a highly recommended best practice but not a strict requirement. However, recent changes from major mailbox providers like Google and Yahoo have effectively made it mandatory for many senders, transforming it from a 'nice-to-have' into a 'must-have' for reliable email delivery. Let's break down what this means for you.
The evolution from 'recommended' to 'required'
Technically speaking, you can still send an email without a DMARC record. Many sources will correctly state that it isn't an absolute requirement for the simple act of transmitting a message. This is because email protocols themselves don't mandate its presence.
However, this technicality is becoming irrelevant. The practical reality is that for your emails to actually be delivered to the inbox, especially at scale, DMARC is now essential. As Mailgun points out, the rules of the game have changed, particularly for bulk senders.
The Gmail and Yahoo bulk sender requirements
In February 2024, Google and Yahoo rolled out new sender requirements to combat spam and protect their users. These rules specifically target 'bulk senders', which they define as domains sending more than 5,000 emails per day to their respective mailboxes.
If you fall into this category, DMARC is no longer optional. The core requirements for bulk senders now include:
- Email Authentication: You must have both SPF and DKIM set up for your sending domain.
- DMARC Record: You must have a DMARC record published in your DNS, even if it's set to a simple monitoring policy of p=none.
- Easy Unsubscribe: Your messages must include a clear, one-click unsubscribe link in the email header.
- Low Spam Rates: You must maintain a low spam complaint rate.
Failing to meet these standards can have severe consequences, leading to your emails being outright blocked or sent directly to the spam folder, which torpedoes your sender reputation and campaign performance.
Why every sender should use DMARC
Even if you don't send 5,000 emails a day, implementing DMARC is a critical step for security and deliverability. It's a powerful tool that works on top of SPF and DKIM to protect your domain from being used in phishing and spoofing attacks. When you consider the damage a malicious actor could do by impersonating your brand, setting up DMARC becomes a clear choice.
Think of it this way: SPF says which servers are allowed to send for you, and DKIM provides a digital signature to verify the message. DMARC tells receiving servers what to do if a message fails those checks. It ties everything together into a coherent policy, which mailbox providers love to see. It signals that you are a responsible sender who takes email security seriously, which can only help your deliverability.
Your first steps with DMARC
Getting started with DMARC doesn't have to be intimidating. You don't need to immediately block all unauthenticated mail. The best approach is to start with a monitoring-only policy.
A starting record might look something like this: v=DMARC1; p=none; rua=mailto:youremail@yourdomain.com. This policy, p=none, ensures your email flow isn't disrupted. The rua tag tells receivers where to send aggregate reports. These reports are invaluable, giving you visibility into who is sending email on behalf of your domain. Once you're confident that all your legitimate mail is authenticating correctly, you can gradually move to a stronger policy like p=quarantine or p=reject to actively protect your domain.
In conclusion, while a DMARC record may not be technically mandatory for a server to transmit an email, it is practically mandatory for successful email delivery in today's landscape. For bulk senders, it's a non-negotiable requirement from Gmail and Yahoo. For everyone else, it's an essential security and deliverability best practice that shouldn't be ignored.
