Microsoft has new email rules starting May 5th

If you send bulk emails to Outlook, Hotmail, or Live.com addresses, Microsoft has new rules starting May 5, 2025. Miss these requirements, and your emails will struggle to reach your customers' inboxes (some may be rejected entirely).

Here's everything you need to know, explained in plain English.

Quick Summary: What's Happening?

Starting May 5, 2025, Microsoft will reject emails from bulk senders (5,000+ emails/day) that don't meet their authentication requirements. This affects anyone sending to:

@outlook.com
@hotmail.com
@live.com

The good news: If you already comply with Gmail and Yahoo's requirements from 2024, you're mostly set. Just a few Microsoft-specific tweaks needed.

The great news (if you're a Bento customer): We've already implemented these requirements for you. You don't need to do anything other than visit the DNS dashboard and check you've added everything.

Why Should You Care?

Think of email authentication like showing your ID at a secure building. Without proper ID (authentication), you can't get in. Starting May 5th, Microsoft is becoming that strict security guard who won't let you pass without proper credentials.

What happens if you ignore this:

Your emails get rejected with error: 550; 5.7.515 Access denied
Your customers don't receive important emails like password resets, order confirmations, or marketing emails
Your email reputation suffers
You lose revenue from failed email campaigns

Who This Affects

You're a "bulk sender" if you send 5,000+ emails per day to Microsoft consumer domains. This includes:

All emails from your domain count together. If [email protected] sends 3,000 and [email protected] sends 2,500, that's 5,500 total.
Bounced emails count too. Even failed deliveries add to your total.
Business emails (like [email protected]) are NOT affected (yet).

Real Example:

An e-commerce company with multiple departments:

Marketing team: 2,000 emails/day
Order confirmations: 1,500 emails/day
Customer support: 1,000 emails/day
Abandoned cart reminders: 800 emails/day Total: 5,300 emails/day = Bulk sender

The Requirements: Explained Simply

1. SPF (Sender Policy Framework)

What it is: A list of servers/IPs allowed to send email for your domain.

Think of it like: A guest list at an exclusive party. If the bouncer (Microsoft) doesn't see your server on the list, you can't get in.

What you need to do: Update your SPF record to include every provider that sends email for you.

What you need to do (if you're a Bento customer): If you've added your DNS records, we've already handled this automatically for you. It is done elegantly so won't clash with your existing SPF records.

2. DKIM (DomainKeys Identified Mail)

What it is: A digital signature proving your email hasn't been tampered with.

Think of it like: A wax seal on an old letter. If the seal is broken, you know someone messed with it.

What you need to do: Set up signing keys in your DNS and configure your email system to sign messages.

What you need to do (if you're a Bento customer): If you've added your DNS records, we've already handled this automatically for you.

3. DMARC (Domain-based Message Authentication)

What it is: Instructions telling Microsoft what to do if your email fails SPF or DKIM checks.

Think of it like: Instructions to the bouncer: "If someone claims to be from my company but isn't on the list, don't let them in."

What you need to do: Create a DMARC policy (minimum p=quarantine) that aligns with SPF or DKIM.

Timeline: Mark Your Calendar

📅 May 5, 2025
├─ Authentication requirements enforced
├─ Non-compliant emails REJECTED (not just filtered)
└─ Error: 550; 5.7.515 Access denied

⏰ NOW
└─ Start preparing immediately

Step-by-Step Compliance Checklist

✅ Step 1: Check Your Current Status

Use free tools to verify your authentication:

✅ Step 2: Set Up SPF (not required for Bento customers)

List all services that send email for you (ESP, CRM, etc.)
Create SPF record: v=spf1 include:spf.protection.outlook.com -all
Add to your DNS as a TXT record
Test using: nslookup -type=txt yourdomain.com

✅ Step 3: Configure DKIM (not required for Bento customers)

Generate DKIM keys (your email provider usually helps)
Add public key to DNS
Enable DKIM signing in your email system
Verify signatures are working

✅ Step 4: Implement DMARC

Start with: v=DMARC1; p=none; rua=mailto:[email protected]
Add as TXT record to _dmarc.yourdomain.com
Monitor reports to ensure alignment
Gradually increase to p=quarantine or p=reject

✅ Step 5: Additional Best Practices

Valid From/Reply-To addresses: No more "noreply@" - use real, monitored addresses — if your address bounces you'll run into issues (IMPORTANT).
Easy unsubscribe: Clear, visible unsubscribe links in every marketing email
List hygiene: Remove bounced and inactive addresses regularly
Honest subject lines: No clickbait or misleading headers

Common Mistakes to Avoid

❌ "I'll just use noreply@ addresses"

Microsoft wants real addresses that can receive replies. Consider using:

❌ "My ESP handles everything"

Even if you use Mailchimp, SendGrid, etc., YOU must set up DMARC in your DNS.

❌ "I'll wait until May to start"

Authentication setup can take weeks to properly configure and test. Start now.

What Happens If You're Not Ready?

Starting May 5, 2025, non-compliant emails will see:

550; 5.7.515 Access denied, sending domain [YourDomain.com] 
does not meet the required authentication level.

Your emails won't reach recipients. Period.

Tools & Resources

Testing Tools:

SPF Check: SPF Record Checker
DKIM Validator: DKIM Record Checker
DMARC Tester: DMARC Record Checker

Email Service Provider Guides:

Or, if you're a Bento customer, pop into your dashboard and click "Sender Authentication" to go through our tailored guide.

FAQs

Q: Do these rules apply to transactional emails?

A: Yes, if you send 5,000+ emails/day total. However, one-click unsubscribe is only required for marketing emails. We still recommend setting it up for all emails just to be safe.

Q: What if I send less than 5,000 emails/day?

A: You're not required to comply, but following these practices improves deliverability anyway.

Q: Can I get an extension past May 5?

A: No. Microsoft has been clear about the deadline.

Q: Do subdomains count separately?

A: No. Email from news.company.com and support.company.com count together toward the 5,000 limit.

Quick Wins: Start Here

If you're overwhelmed, start with these three actions today:

Check your current authentication across any provider that sends email for you using Aboutmy.email.
Contact your email service provider about their Microsoft compliance
Set up DMARC monitoring (even at p=none) to see who's sending as you. If you use something like Cloudflare this could be as simple as 1-click.

The Bottom Line

Microsoft's new requirements aren't just bureaucracy—they're about making email safer for everyone. By implementing proper authentication, you're not just avoiding rejection; you're building trust with your recipients and protecting your brand.

Remember: May 5, 2025 isn't a suggestion—it's a deadline. Start preparing now.

Need help? Most email service providers offer authentication setup assistance. Don't wait until the last minute to ask for help. If you're a Bento customer, you can book a call anytime to step through it.