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Delivery problems

Why are my emails being blocked or delayed by Microsoft/Hotmail?

R

E

Delivery problems

Why are my emails being blocked or delayed by Microsoft/Hotmail?

There are several potential reasons for Microsoft delivery issues. Here’s how to diagnose and fix them:

  1. First, check your metrics in Email Signals:

  • If your bounce rate is above 2%, you’ll need to clean your lists.

  • If spam complaints are above 0.1%, review your content and opt-in practices.

  • Look at your delayed rates to Microsoft domains.

  • Check Message Events for specific Microsoft bounce codes.

  • [Optional with Inbox Tracker] Review reputation using SNDS or GPT.

  1. Next, review any recent changes:

  • Have you sent more email than usual?

  • Did you change your email content?

  • Are you mailing to new lists?

  • Did you modify your authentication settings?

  1. To resolve the issue:

  • Verify your authentication (SPF, DKIM, DMARC) in Email’s Domains section.

  • Remove inactive subscribers (no engagement for 6+ months).

  • Stop sending to bounced addresses.

  • Process unsubscribes immediately.

  • Keep your sending volume consistent.

  • Include clear unsubscribe links.

  • Use clear subject lines.

  • Include your physical mailing address.

Contact Email Support if:

  • You’ve completed all these steps.

  • Your metrics are within normal ranges.

  • Issues continue for more than 48 hours.

  • You see unusual bounce codes.

  • You need SNDS data for your dedicated IPs.

Most blocks clear automatically within 24-48 hours if you follow good sending practices.

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Newsletter

Stay up to date with Bird through weekly updates to your inbox.

Bird VAT number: NL 850209092B01, KVK number: 51874474

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Bird VAT number: NL 850209092B01, KVK number: 51874474