We have deployed exchange at both AD sites....one site exchange receives mail from internet and forward to other site echange via internet vpn tunnel...The problem is, I allways see large queuesof mail to be delivered to my other site....an average ping response time between two site is 350 ms......and the network link is consistant.....this problem was not there in old exchange 5.5..... can some one help where to look for.... thanx

With Exchange 5.5 you probably used a site connector or a X400 connector. With later versions of Exchange this changes to SMTP. Some firewalls use filters on SMTP and therefore creates delays and even impossible to use SMTP between Exchange servers. see if your firewall is using some kind of SMTP filtering.