Index: lisp/pop3.el
===================================================================
RCS file: /usr/local/cvsroot/gnus/lisp/pop3.el,v
retrieving revision 6.23.2.2
diff -u -r6.23.2.2 pop3.el
--- lisp/pop3.el	22 Aug 2004 21:48:11 -0000	6.23.2.2
+++ lisp/pop3.el	30 Aug 2004 16:43:52 -0000
@@ -55,7 +55,14 @@
 values are 'apop.")
 
 (defvar pop3-leave-mail-on-server nil
-  "*Non-nil if the mail is to be left on the POP server after fetching.")
+  "*Non-nil if the mail is to be left on the POP server after fetching.
+
+If the `pop3-leave-mail-on-server' is non-`nil' the mail is to be
+left on the POP server after fetching.  Note that POP servers
+maintain no state information between sessions, so what the
+client believes is there and what is actually there may not match
+up.  If they do not, then the whole thing can fall apart and
+leave you with a corrupt mailbox.")
 
 (defvar pop3-timestamp nil
   "Timestamp returned when initially connected to the POP server.
Index: texi/gnus.texi
===================================================================
RCS file: /usr/local/cvsroot/gnus/texi/gnus.texi,v
retrieving revision 6.603.2.4
diff -u -r6.603.2.4 gnus.texi
--- texi/gnus.texi	26 Aug 2004 09:59:57 -0000	6.603.2.4
+++ texi/gnus.texi	30 Aug 2004 16:43:53 -0000
@@ -13528,10 +13528,16 @@
 
 @end table
 
+@vindex pop3-movemail
+@vindex pop3-leave-mail-on-server
 If the @code{:program} and @code{:function} keywords aren't specified,
 @code{pop3-movemail} will be used.  If the
 @code{pop3-leave-mail-on-server} is non-@code{nil} the mail is to be
-left on the POP server after fetching.
+left on the @acronym{POP} server after fetching when using
+@code{pop3-movemail}.  Note that POP servers maintain no state
+information between sessions, so what the client believes is there and
+what is actually there may not match up.  If they do not, then the whole
+thing can fall apart and leave you with a corrupt mailbox.
 
 Here are some examples.  Fetch from the default @acronym{POP} server,
 using the default user name, and default fetcher: