You can check the message headers to find out where a particular message was delayed. Headers contain delivery information about messages including a list of which machines a message passed through on its way from the sender to the recipient.

To see all header information for a particular message open the message and click the "Full Headers" link, located on the upper-right side of the page. Your message is then displayed with full headers were you'll see one or more entries for "Received." This is the record of deliveries, which can be slightly more complex than this basic example.

This says that mta1.yahoomail.com (a Yahoo! Mail computer) received a message from sender4.lodo.merc.com on 22 July 2005 at 3:13:23 PM PDT (seven hours behind GMT).

If there's more than one Received header, the message was relayed through several machines. Received headers are read from bottom to top; that is, the topmost header was the last to be added. Please note that there is often a slight difference between clocks on different computers, so the times might be slightly out of synch, but the path traveled should be clear.