When using this code to delete an IMAP message:
<?
$objmbox = imap_open("{localhost}", "user", "password", OP_READONLY) || die("Can't connect");

$check = imap_mailboxmsginfo ($objmbox);
print "Messages before delete: $check->Nmsgs<br>\n" ;
imap_delete ($objmbox, 1);
$check = imap_mailboxmsginfo ($objmbox);
print "Messages after  delete: $check->Nmsgs<br>\n" ;
imap_expunge ($objmbox);
$check = imap_mailboxmsginfo ($objmbox);
print "Messages after expunge: $check->Nmsgs<br>\n" ;
imap_close ($objmbox);
?>

I get: 

Messages before delete: 370
Messages after delete: 370
Messages after expunge: 370

This leads me to believe that the delete function or the expunge function is not working.

I also tried using "{localhost}INBOX" to connect and that didn't work either.

This is how I compiled php:
./configure --with-mysql --enable-track-vars --enable-trans-sid --with-apxs=/usr/local/apache/bin/apxs --with-ftp --with-imap

I am using IMAP-4.7c.  compiled with the default ./configure
OS is FreeBSD 4.1-RELEASE

schu