[MWE]

I have Outlook 2003 SP3 running on 3 computers. The load is identical on all three machines . When I compose an email and click on Send what then happens varies from computer to computer. On two of the computers, the item is sent to the OutBox and then immediately sent to the ISP server. On the third, the item sits in the OutBox until the Send/Receive button is clicked in the Standard ToolBar. As best I can tell, all three machines have Outlook configured identically.

I have looked through the Send/Receive options but can find nothing that suggests a control for "send immediately" other than "Send Immediately When Connected" and that is checked.

Any thoughts?

[MWE]

A little clarification regarding the specific computers. Two are laptops (IBM T40 and Dell M4300), one is a desktop (Dell9100). One laptop and the desktop do not exhibit this problem; the Dell M4300 does. The two computers that do not have the problems have recent (last few months) complete rebuilds (hard drives were going; drives were replaced and ground up reinstall of opsys and all programs done). However, the same MSOffice CD was used for install on all computers and all installs of Office2003 were upgraded to SP3. The Dell M4300 is a year old with factory installed opsys.