If you are suffering from delayed messages or you need to better understand the message path for inbound mails the place to look is the SMTP message header.

In outlook you can get this by right clicking on the message and choosing properties. In the window displayed the header information is in a box towards the bottom.

The text in here can be very difficult to follow - especialyl if it passes through several time zones.

The following website allows you to paste the header data directly in and then it will show you each server that touched the message and the time between each stage.

http://www.mxtoolbox.com/EmailHeaders.aspx