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Microsoft Defender for Office 365 Blog
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Strengthening Email Ecosystem: Outlook’s New Requirements for High‐Volume Senders

Puneeth's avatar
Puneeth
Icon for Microsoft rankMicrosoft
Apr 02, 2025

This applies to Outlook.com - our consumer service, which is supporting hotmail.com live.com and outlook.com consumer domain addresses.

April 29th Update - Changes have been made to the action take on messages that do not meet requirements, please see details below. Introduction In an era where email remains one of the most widel...
Updated Apr 30, 2025
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awareness & training
email protection basics
Cdary's avatar
Cdary
Brass Contributor
Jun 26, 2025

Because it takes less time for Microsoft to retrieve the record from its DNS cache than it does to wait for the response to a DNS query

rsetht's avatar
rsetht
Copper Contributor
Jun 27, 2025

Obviously - but if the cache is stale, be it after 12 or 48 hours, they're still going to have to query the actual DNS.   You've postponed the problem, potentially, but not really now that we're 2 weeks into the issue.

  • Cdary's avatar
    Cdary
    Brass Contributor
    Jun 28, 2025

    DNS timeouts are a random issue that occurs x% of the time (x could be around 1); the less you try, the less likely you are to get unlucky. Once Microsoft has successfully retrieved the DNS value, it is best to keep it as long as possible before it is forced to try again.