This article describes the issue about failed delivery attempts for UDT on an additional poller multiple.
UDT version 3.2.3 and earlier with additional polling engines
This is issue is caused by a bug.
Verify if you are experiencing the same issue by running this query in database manager:
Volume:\Program Files (x86)\SolarWinds\Orion\DatabaseManager.exe
SELECT TOP 1000 * FROM [dbo].[Subscriptions] ORDER BY FailedDeliveryAttempts DESC
To fix this issue, perform the steps below:
DELETE FROM dbo.PendingNotifications DELETE FROM dbo.Subscriptions DELETE FROM dbo.SubscriptionTags
8. Install the hotfix provided in this link: http://downloads.solarwinds.com/solarwinds/Release/HotFix/UDT-v3.2.3-HotFix1.zip