send/ receive Outlook 2002 SP3

Outlook is holding outgoing sent message in "outbox",    it has stopped automatically sending them.

I've checked the setting in "mail setup"  and it still shows:   "send immediately when connected."

What else can be done to remedy this as it has previously worked automatically-------  Dimension 8200 XP about 5-6 years old.

Incoming mail also requires "send/receive" button to be clicked,   or F9 also works,  and they work immediately,    so slowness is not an issue,   it's just that it requires the extra step,   and I would like to restore this to the way that it was before.

What can be done?

Thanks.