You are using Exclaimer Signature Manager Exchange Edition or Exclaimer Mail Disclaimers.
The Sent Items Update feature is enabled and you find that there are a lot of sent items in the C:\ProgramData\Exclaimer Ltd\Mail Disclaimers\SentItemsUpdate\Cache directory, waiting to be updated.
If the Sent Items Update service is not working, the server is likely to be low on disk space. View the Exclaimer Sent Items Update Service application event log for any errors and refer to Solution 6 in this Knowledge Base article .
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