I recall Outlook versions 95, 97, 98, 2000, 2002, 2003, 2005, 2007, 2008 and 2010.
I can't tell if my idea applies to all versions.
Computer has multiple excel's running each which periodically sends emails. This obviously creates eventually quite a lot of emails to be sent and as it turns out too many in the sent folder causes eventually mail sending go all haywire. Not sure why but that's just how it is.
Solution is simple: Keep sent message folder not too crowded. However manually removing those gets annoying. And messages are supposed to be hold for a while so not storing them in sent folder isn't an option.
Any way outlook(or windows) could be configured to automatically delete messages from sent folder after message is X days old?
Using XP with outlook express 6.