When trying to get the meeting notifications to work, I initially recieved this error:
Dead Failure Reason:User Sametime Development/Lotus Notes Companion Products (Sametime Development/Lotus Notes Companion Products@Domain) not listed in Domino Directory
After enabling smtpclientdebug=1, I was seeing that the error was actually similar to this: Meeting notification email to moderator
Specifically, the error is: SMTPClient: Error parsing from address
The key part of this error is that it's an error parsing from address. To make a long story short, I ended up having to open STConf.nsf in Domino Designer, then opening the the "sendnotification email" script library. In the sub used for notifications, I had to modify what was being used for the sender's address.
One note is that you should create a Sametime Admin account on the Domino server as well as on the Exchange server. In Exchange, you could create a Sametime Admin group to receive the replies if you would like. Here's what I changed to not only solve the issue above, but to also make the Outlook Client display a name in the Inbox folder.
Look for the following If loop and replace it with the following code down to the line that is: Set header = body.CreateHeader("Sender")
If (sendEmailFrom = "") Then
'sendEmailFrom = meetingDoc.STCreator(0)
sendEmailFrom = "firstname.lastname@example.org"
' The following three are the best way to ensure that the client renders the
' sender's address correctly. When modifying the principal field, Domino must
' be able to resolve the address in the local directory (from my understanding and
' prior troubleshooting).
doc.From = "Sametime Admin
doc.Principal = "Sametime Admin
doc.replyto = "Sametime Admin
' You can just use the internet address for the following sender fields.
doc.SendFrom = sendEmailFrom
doc.DisplaySent = sendEmailFrom
doc.AltFrom = sendEmailFrom
doc.INetFrom = sendEmailFrom
doc.tmpDisplayFrom_Preview = sendEmailFrom
doc.tmpDisplayFrom_NoLogo = sendEmailFrom
doc.tmpDisplaySentBy = sendEmailFrom