This is problem with SquirrelMail 1.4.2
I try another version 1.4.1 and it has same problem.
When I click INBOX.
The latest message show Sender as "Unknown" and
subject as "No subject".
Another message below this message don't have any
problem. Only top message has problem.
If I click top message to see detail.
The detail display correctly.
I din't know how to fix this problem.