Provider limits
Outlook / Microsoft 365 Sending Limits vs Cold Email Volume
Understand Exchange Online service limits and why a cold email operating limit should remain a separate decision.
5 free checks per day · 20 with a free account
DMARC Checker
Read a DMARC record and see the policy, reporting and alignment tags.
Check a domain's DMARC policy
We read the _dmarc TXT record and explain each tag.
Rolling out DMARC
Start with p=none and an aggregate report address so you can see who sends as your domain. Once SPF and DKIM align for your real senders, move to quarantine and then reject.
Publish exactly one DMARC record. Multiple records make the policy invalid.
Error code guides
Common errors and how to fix them
- DMARC record missing (DMARC_MISSING)
- Multiple DMARC records (MULTIPLE_DMARC_RECORDS)
- Invalid DMARC policy (INVALID_POLICY)
Resources
Related guides
Quick reads to help you plan audiences, sending volume, sequences and measurement before launch.
Deliverability
Gmail and Yahoo Sender Requirements: What They Mean for Cold Email
SPF, DKIM, DMARC, one-click unsubscribe and the 0.3% spam-rate ceiling: what Google and Yahoo require from senders and how cold email teams should apply it.
Deliverability
SPF, DKIM and DMARC for Cold Email
A practical explanation of the three core email authentication mechanisms and how they work together.
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