ICal Server mail notification generates malformed Reply-To header

Question

When a mail notification (invitation) for an event is sent by iCal Server running on Snow Leopard Server to an outside email address, an apparently malformed "Reply-To" header similar to
[email protected]
is always inserted into the message. As the above address is not a valid one, the recipient is unable to reply to the event invitation. The "From" and "Return-Path" headers always indicate the correct email address "[email protected]".
Has anyone encountered this issue, or more importantly, know of a solution?

Answer 1

Remember - email addresses are technically only the @domain.com address. The suffix information is only a user of that domain.
ALL email sent regardless of who or how it is addressed before the @ is technically irrelevant to the end client (outlook, thunderbird, etc..)
Email is really only a DNS operation. The @domain.com is resolved somewhere in the cloud (no one really wants a boring DNS resolution lesson here....) to your domain server. In your public DNS records there are MX records which tell anyone trying to send email to your DOMAIN (not users) what mail servers you have, where they can be located, and in what priority they are used (if multiple mail servers are used.)
Once the email finds its way to your email server, it internally resolves the info before the @ to it's user directory (AD, OD, whatever) and then the mail server processes the message and sends it along to the user if it validates. But it still arrives at your mail server regardless if it is correct or not.
You can try this test yourself... (as long as copy all undeliverable mail to: is enabled in your server admin)
Send an email to some made up email address... [email protected].
It will still be resolved to your email server and "delivered" to your "copy undeliverable email to:" address. Even though it is not a valid user of your domain.
So, what does all that crap have to do with the topic? When you hit reply to an third party ical invite (because internal ical users don't use email for invites) - everything in front of the @domain.com is irrelevant in the reply process. And this applies to all email clients. The message is resolved and sent back to your @domain.com email server. So when you see the icalserver+blah blah blah [email protected] it is a correct address and all email clients only see the info after the @ for routing and send it to your email server.
It is once it hits the Mac Server does the magic happen. In the setup of ical, you specify an ical email address for this specific third party email invite function. Hence, the [email protected] address.
Mac email server has built in support for sub-addressing and this is where everything AFTER the "+" is resolved internally in the ical server.app. iCal uses this information to process the invite.
So, in closing... it has to be a Mac server for this function to work.
Hope I didn't stray to far from your question.
Scott