Hello, We are using Exchange 2003 sp2 with Outlook 2007 and it is set to send all messages to the SMTP proxy that is built into our firewall. When scheduling events in the Outlook calendar inviting external people it doesn't always send the invite. It just sits in the queue. It doesn't do this for all external people just some. I've watched the SMTP proxy logs on our firewall during this and I don't even see the Exchange server trying to connect to send the invite emails. I'm at a loss as to why this is happening or how to even trouble shoot this. Has anyone seen this before? Any thoughts or ideas would be greatly appreciated. It seems to happen for certain users sending to certain external people everytime. They can sned emails to the external people no problem but the calendar invite just doesn't go. Thanks, Limbo

When you say it is for certain external users; are they at the same domain? Is it a case of not being able to send the invites to certain domains? Does the sender ever receive an NDR?TBrennan

They are different domains but the odd thing is the user can send an email to the same external users and it goes through fine. They do eventually recieve an NDR. To trouble shoot and rule things out I set the Exchange server to send email directly out and not go through the SMTP proxy and I get the same outcome so I know it's not the proxy.

Hi, Could you please try this hotfix? A meeting update message or a meeting cancellation message from an Exchange 2003 user is not delivered to an Exchange 2007 user Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Hi Limbo, Do you have any update?Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

I haven't applied the hotfix yet. I plan on doing it this evening. I'll let you know if it fixed the issue. Thanks,

I applied the hotfix and so far it seems okay. The company is closed until July 6th for the holiday. I'll let you know how it goes once everyone comes back and it gets a full testing.