Your network contains a single domain named contoso.local.
You have an Exchange Server 2016 organization that uses a single external SMTP namespace of contoso.com. You establish mail flow to and from the Internet.
You plan to deploy a customer relationship management (CRM) solution. The CRM solution will have its own SMTP server and must be able to receive email sent by using various addresses in contoso.com. The addresses will not be managed by the Exchange Server organization.
You need to recommend a solution to ensure that the CRM solution can receive email from the Internet.
The solution must ensure that internal users can all receive email.
Which two action should you recommend? Each correct answer presents part of the solution.
NOTE: Each correct selection is worth one point.
Correct Answer: B,E
Explanation/Reference:
External relay domain: No recipients in the authoritative domain exist in the Exchange organization, so you shouldn't enable Recipient Lookup for the domain.
The Send connector that you configure for non-existent recipients in the external relay domain is sourced on an Edge Transport server or Internet-facing Mailbox server.
Incorrect Answers:
Internal relay domain: If all recipients in the internal relay domain exist in the Exchange organization (including mail contacts and mail users), you can enable Recipient Lookup for the domain.
If some or none of the recipients in the internal relay domain exist in the Exchange organization, you shouldn't enable Recipient Lookup for the domain.
References: https://technet.microsoft.com/en-us/library/bb124423(v=exchg.160).aspx