We had a problem with Outlook 2007 suddenly not wanting to send emails waiting in the outbox. They all had an icon we had not seen before, a clock on an envelope.
I found that the pst file had exceeded its maximum (it was almost 2GB). So we
- deleted many old emails,
- removed them (by highlighting all the delete folder entries and pressing [shift][del]),
- compacted the pst file - go to [file] [data file management] and double-click your file, press compact now.
It takes a while but if you watch the pst file you will see it getting smaller.
I made copy of the pst file (with outlook closed) just beforehand, just in case.
Then loading outlook (maybe once or twice, maybe after creating another email), the icons had gone and the emails went too.
I hope this helps someone.
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