outlook calendar accept invite issue

Question

We have two separate email system environment , the first exposed that mean with an MX records the second not exposed. All users belong to the second environment will be able to receive an email only if the sender will use the first domain (john@firstdomain.com). The first email system (exchange server 2016) will consider the second users as a contacts and when is going to receive one email belong to the second users group will convert them into " john@secondomain.com" and will deliver to the second email system for the final user delivery.
An EDGE server will re-convert the email for the outbound emails.

Every things is working fine except when a receiver accept the calendar invite organised by a second group users. It will generate an error: domain not found. It because in that case the invite header has as a reply -"sender"- john@seconddomain.com and not john@firstdomain.com and probably because the EDGE servers are not able to convert as well also this type of message/request header.

Is there a solution or a way to manipulate the "accept" invite header?

Thanks

Answer 1

Hi @Marc ,

Before we move on, could you help confirm the things below so that we can understand better about the current situation:

1. By "An EDGE server will re-convert the email for the outbound emails.", do you mean you are using Address rewriting on Edge server for outbound messages from the second domain?
2. Aside from the issue when a receiver accepts the meeting request sent by a second domain user, what if a receiver replies to a normal message sent from a user who belongs to the second environment?
3. Is "domain not found" the entire error? If not, would you mind removing all personal information involved and share a more detailed error message for further analysis?

Furthermore, regarding your concern about the message header, according to the explaination in the official document below, for outbound messages, both the "sender" and the "reply to" fields are rewritten by Address rewriting:
Address rewriting on Edge Transport servers

Is this corresponding to what you see on your end, or by "invite header has as a reply -"sender"- john@seconddomain.com", you mean the reply-to header is not rewritten? If possible, you can share a partial of the problematic message header after removing all private data.

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