Using Firewall has stopped the client refreshing itself

[Daniel101]

We have just had a firewall installed and been issued an external I.P address for our exchange server (5.5). The server works fine running off the DMZ port on the firewall and internal users can access their mail. The problem comes when users send internal or external mail. It seems that users receiving or sending mail will not do so until the click someone within their exchange\outlook client. Items will remain in the outbox until clicked on, but will then send O.K. Does anyone have any ideas whether this is an exchange server\client problem or a networking one and if so how it can be resolved?<br><br>Thanks<br><br>Dan

 

[Guest_imported]

I have similar experience.&nbsp;&nbsp;Here is my theory but not 100% sure.<br><br>Since you are behind firewall, you are probably using Network Address Translator (NAT) and private IP address.<br><br>When Exchange tries to communicate (email notification is in sent in UDP) with an Outlook Client, it can only communicate thru the private IP address.&nbsp;&nbsp;This fails if there is a router in between cause the router will not know how to route the private IP address.&nbsp;&nbsp;This is why you won't get email.<br><br>For Outgoing email:&nbsp;&nbsp;since Outlook cannot receive email from Exchange, it will simply assume there is no connection to the Exchange.&nbsp;&nbsp;The TCP session will time out.&nbsp;&nbsp;When Outlook tries to send, it cannot due to no TCP session.<br><br>When you click on something, a new TCP session is established.&nbsp;&nbsp;Theis is when you can receive and send emails.<br><br>Would someone confirm my theory and a solution?<br><br>Thanks<br><br>Ken