[Declude.JunkMail] Explanation of Status and X-UIDL Headers

[Ron Harris]

What do the below lines indicate?  The two lines are snippets from my internet headers of an e-mail I received.  I understand all the header lines except these.  Maybe point me in the direction of where I can read about these headers?  Thanks. -ron   Status: U X-UIDL: 342581740