Simple example on how to read body message of the recent mail.

<?php
$imap = imap_open("{pop.example.com:995/pop3/ssl/novalidate-cert}", "username", "password");

if( $imap ) {
    
     //Check no.of.msgs
     $num = imap_num_msg($imap);

     //if there is a message in your inbox
     if( $num >0 ) {
          //read that mail recently arrived
          echo imap_qprint(imap_body($imap, $num));
     }

     //close the stream
     imap_close($imap);
}
?>

Please note that the UID is NOT unique.
UID of the email may be not unique on the server (2 messages in different folders may have same UID).

Basically, don't use the UID as a unique identifier.