Bounces read “550 5.7.509: Access denied, sending domain does not pass required authentication”.
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What this means
Your domain has no SPF record at all, or the record is syntactically broken, so Microsoft can't verify any sender.
How to fix it
Step 1. Check whether an SPF record exists (our free checker shows it instantly).
Step 2. If missing, publish one TXT record at your domain root: v=spf1 include:<your-provider> ~all.
Step 3. If present, fix syntax errors — a single typo invalidates the whole record.
Step 4. Never publish two SPF records: receivers treat that as a permanent error.
Frequently asked
How long until fixes take effect?
DNS changes propagate within minutes to 48 hours. Mailbox providers pick up the new records on their next check — most senders see bounces stop within a day of correct configuration.
Does this apply if I send fewer than 5,000 emails a day?
Formal enforcement targets bulk senders, but partial authentication already costs you inbox placement at every volume — and spoofing protection matters regardless of how much you send.
Can I just ask my hosting provider to fix it?
Hosting support can add DNS records for you, but they don't know which services send as your domain. You (or a monitoring tool reading your DMARC reports) have to provide that list — that's the actual hard part.
Don't want to babysit DNS records? DMARCKeeper monitors your reports, names every sender, and walks you to full p=reject protection. Start free monitoring →