Hi @Attila Dob,
Thank you for posting in this community.
First, we need to verify that the deleted retention policy still exists.
1.Please install the Exchange Online PowerShell module.
2.Run the following command to get all the policies in your organization to see if they contain the deleted policy. (You can also add -Identity to find your deleted policy based on the policy name.)
Reference: Get-RetentionCompliancePolicy
#This example displays summary information for all retention policies in your organization.
Get-RetentionCompliancePolicy
#This example displays detailed information for the policy named "Regulation 123 Compliance", including accurate values for the DistributionStatus and *Location properties.
Get-RetentionCompliancePolicy -Identity "Regulation 123 Compliance" -DistributionDetail | Format-List
Then, if the policy still exists, run the following command to remove the policy. If everything is fine, skip this step. Reference: Remove-RetentionPolicy
#This example removes the retention policy Business Critical.
Remove-RetentionPolicy -Identity "Business Critical"
Finally, this policy deletion starts the deletion from the server side, and it will take 24 hours or more before it takes effect. So, we suggest you check back in a few days to see if the problem still exists.
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