Emails not being delivered to recipient in Outlook 2010

Hi,

I have an issue whereby emails sent from Outlook 2010 on a Windows 7 Professional SP1 machine are not reaching the recipient. The machine is in a domain environment managed by a Windows Server 2003 sp2 sbs box.

The emails are shown in sent items, I do not get a bounceback. I requested a delivery receipt on a few of them which I never received. The client CAN receive external and internal emails.

AVG is installed on the machine but I still have the same issue when it is fully disabled.

I can send successful emails from OWA internally and externally. When setting the email account up on my machine whilst connected to the customer via VPN I can send emails fine.

The customer's emails are managed by a smart host "gconnect.net".

I called gconnect and they said they could only see the emails sent via OWA and when I set the account up on my Outlook. None of the ones sent from the customer's machine are hitting the smart host.

Also, because I can send from https://localhost/exchange on the SBS Server, logged in as the user, shows that the emails can be sent out from the server. This says to me that the emails aren't even hitting exchange from the client. Gconnect have a customer portal where I can add users to the "Valid Recipeints List" this basically enables them to send and receive through the smart host externally. The user in the valid recipients list.

I have run a repair on MS Office 2010 and rebooted with no change. I also ensured that windows firewall was turned off for domain networks.

I had a break through yesterday evening where I disabled the AVG Outlook add-in and emails started to flow as normal! This morning, I come in and emails are not sending with or without the AVG Outlook add-in.

AVG has been uninstalled and re-installed. I'm convined this is a problem with AVG, if anyone can shed light on this it would be greatley appreciated.

Thanks,