diff -r 73a3a6b1af36 src/lib-storage/index/index-mail.c
--- a/src/lib-storage/index/index-mail.c	Sun Nov 18 20:13:59 2007 +0200
+++ b/src/lib-storage/index/index-mail.c	Tue Nov 20 05:48:19 2007 +0200
@@ -763,12 +763,26 @@ index_mail_alloc(struct mailbox_transact
 
 static void index_mail_close(struct index_mail *mail)
 {
-	if (mail->data.parser_ctx != NULL)
-		(void)message_parser_deinit(&mail->data.parser_ctx);
-	if (mail->data.stream != NULL)
-		i_stream_destroy(&mail->data.stream);
-	if (mail->data.filter_stream != NULL)
-		i_stream_destroy(&mail->data.filter_stream);
+	if (mail->data.stream != NULL && mail->data.stream->v_offset != 0 &&
+	    strcmp(mail->mail.mail.box->storage->name, "maildir") == 0) {
+		/* drop the data that has been read by the client. with partial
+		   fetches we drop only what has been read so far.
+
+		   if we read the mail just to return e.g. virtual size or
+		   bodystructure, v_offset=0 and we don't drop anything since
+		   there's a good chance that the client will soon fetch the
+		   mail body. */
+		int fd = i_stream_get_fd(mail->data.stream);
+		if (posix_fadvise(fd, 0, mail->data.stream->v_offset,
+				  POSIX_FADV_DONTNEED) < 0)
+		       i_error("posix_fadvise() failed: %m");
+	}
+       if (mail->data.parser_ctx != NULL)
+	       (void)message_parser_deinit(&mail->data.parser_ctx);
+       if (mail->data.stream != NULL)
+	       i_stream_destroy(&mail->data.stream);
+       if (mail->data.filter_stream != NULL)
+	       i_stream_destroy(&mail->data.filter_stream);
 }
 
 int index_mail_set_seq(struct mail *_mail, uint32_t seq)
diff -r 73a3a6b1af36 src/lib-storage/index/maildir/maildir-mail.c
--- a/src/lib-storage/index/maildir/maildir-mail.c	Sun Nov 18 20:13:59 2007 +0200
+++ b/src/lib-storage/index/maildir/maildir-mail.c	Tue Nov 20 05:48:19 2007 +0200
@@ -45,6 +45,7 @@ maildir_open_mail(struct maildir_mailbox
 maildir_open_mail(struct maildir_mailbox *mbox, struct mail *mail,
 		  bool *deleted_r)
 {
+	struct index_mail *imail = (struct index_mail *)mail;
 	const char *path;
 	int fd = -1;
 
@@ -62,6 +63,10 @@ maildir_open_mail(struct maildir_mailbox
 	if (fd == -1) {
 		*deleted_r = TRUE;
 		return NULL;
+	}
+	if ((imail->data.access_part & (READ_BODY|PARSE_BODY)) != 0) {
+		if (posix_fadvise(fd, 0, 0, POSIX_FADV_SEQUENTIAL) < 0)
+			i_error("posix_fadvise() failed: %m");
 	}
 
 	if (mbox->ibox.mail_read_mmaped) {