The solution is very simple: empty the folder Sent Items.
It is a long story of getting to the solution. If interested, please read on.
In my office a dedicated artwork processing workstation receives and sends tons of emails everyday. The email program installed is Outlook Express. Artwork attachments are normally high resolution PDFs, JPEGs, etc. Every a few days my colleague asks me to examine this workstation when the symptom comes – emails stay in Outbox after sending, and an error message will popup saying one or more tasks are not completed but not giving details and possible reasons. Actually emails have been delivered many times before my colleague notes the problem.
The Outbox symptom occurs quite randomly. Sometimes even a small email without attachments could incur the problem, but big emails with attachments are more likely to replicate the problem. My previous approaches were focused on rebuilding a new Outbox. I have tried at least the following methods, none of them always work.The effectiveness is random as well.
- Compact all the folds in Outlook Express
- Export and import emails
- Delete Outbox.dbx (Outlook Express will automatically create a new one when it detect Outbox.dbx does not exist)
- Create new Windows user and import emails
- Reinstall Outlook Express and import emails
But all of the above methods could only work for a while. I researched many IT forums. Lots of gurus mention that they face the similar problem and use the above temporary methods. So I had been used to being called for help once in a while.
Today I was called again. While trying my old methods one by one to see if any of these temporarily solve Outbox Symptom, I suddenly had some afflatus. Why I thought Outbox was wrong? I always used “outlook express outbox stuck”, “outlook express outbox stuck” as search terms. It could be Sent Items. My deduction is –
When Sent Items.dbx is getting bigger and bigger, some bugs in Outlook Express make Outlook Express not able to handle reliably a new Sent Item appending to Sent Items.dbx. That is why the Outbox Symptom happens randomly. The email is already sent but because it can not go to Sent Items, it has to stay in Outbox.
Sent Items.dbx on artwork workstation is 3 gigabyte huge. I renamed Sent Items.dbx to Old Sent Items.dbx and deleted Sent Items.bak. Instantly Outbox Symptom was gone. Now I know it is not appropriate to be called as Outbox Symptom. It is Sent Items Symptom. I believe my new solution will be permanent.
Looking backwards, even 3 articles (E-mail does not leave the Outbox, How to troubleshoot mail stuck in the Outbox in Outlook 2000, Error message that Sent Items remain in Outbox) I found from Microsoft knowledge base regarding this Outbox Symptom or Sent Items Symptom whatever did not help much. I do not expect my solution would be collected by Microsoft knowledge base, but I do expect this post can be ranked on top in google “outbox stuck” related search result, helping as many people as possible solving a very simple problem.