diff -r 413dbb37b839 src/lib-storage/index/maildir/maildir-mail.c
--- a/src/lib-storage/index/maildir/maildir-mail.c	Tue Nov 20 04:56:00 2007 +0200
+++ b/src/lib-storage/index/maildir/maildir-mail.c	Tue Nov 20 05:37:56 2007 +0200
@@ -43,6 +43,7 @@ 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;
 
@@ -60,6 +61,11 @@ 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");
 	}
 
 	return i_stream_create_fd(fd, MAIL_READ_BLOCK_SIZE, TRUE);
@@ -386,8 +392,30 @@ static int maildir_mail_get_stream(struc
 	return index_mail_init_stream(mail, hdr_size, body_size, stream_r);
 }
 
+static void maildir_mail_close(struct mail *_mail)
+{
+	struct index_mail *mail = (struct index_mail *)_mail;
+	int fd;
+
+	if (mail->data.stream != NULL && mail->data.stream->v_offset != 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. */
+		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");
+	}
+
+	index_mail_close(_mail);
+}
+
 struct mail_vfuncs maildir_mail_vfuncs = {
-	index_mail_close,
+	maildir_mail_close,
 	index_mail_free,
 	index_mail_set_seq,
 	index_mail_set_uid,
diff -r 413dbb37b839 src/lib-storage/index/maildir/maildir-save.c
--- a/src/lib-storage/index/maildir/maildir-save.c	Tue Nov 20 04:56:00 2007 +0200
+++ b/src/lib-storage/index/maildir/maildir-save.c	Tue Nov 20 05:37:56 2007 +0200
@@ -501,6 +501,13 @@ int maildir_save_finish(struct mail_save
 			ctx->failed = TRUE;
 		}
 	}
+	if (ctx->cur_dest_mail != NULL && !ctx->mbox->ibox.keep_recent) {
+		/* if we're not running from deliver (assume so if
+		   keep_recent=TRUE) and we updated cache file, it's unlikely
+		   we're going to need this mail anytime soon */
+		if (posix_fadvise(ctx->fd, 0, 0, POSIX_FADV_DONTNEED) < 0)
+			i_error("posix_fadvise() failed: %m");
+	}
 	if (close(ctx->fd) < 0) {
 		mail_storage_set_critical(storage,
 					  "close(%s) failed: %m", path);