Set AD User with External Email Address
I am setting up a co-lo for 2 companies in 1 office space. These companies are sister companies but infrastructure has been separated for legal reasons but we are converting into a hybrid office environment where Company A works 2 days at the office, then Company B comes in 2 other days to work in the office. Company B network will be the primary on-site and Company A will be cloud-based. I want to import users from Company A into Company B but instead of having Company B's email addresses I want to call out their email address so any emails will route to their Exchange Server. However, I am running into issues doing this.... If I set their email address as mailto:Email address removed in any of the following attributes email address, ProxyAddress, or mail it fails to route the email to their Exchange server. I ran a message trace on Company A and Company B to track down the email but it does not show on Company A's message trace. On Company B, the message trace says it was delivered. What I found was that Company B's domain assumes it is an internal route even though that domain normaclature does not exist. How can I call out the companyb\user email as mailto:Email address removed? There has to be a way to make this possible. I have a script setup to email users when their passwords are about to expire or MFA passcodes, etc. that creating a mail contact will not be the answer...
Mail routing to external thru EOP
We have Exchange 2016 Hybrid with all users' mailboxes in Exchange online ( shared mailboxes in on-premises EX 2016 servers), currently configured all outgoing email from Exchange Online coming back to on-premises 3rd party host. Now, we would like to configure all outgoing emails from Exchange online using Microsoft EOP, not coming to on-prem 3rd party host. How can i configure Outbound connector in Exchange online to use all outgoing emails routed to EOP? We tested with couple of domains' outbound emails, configured outbound partner connector and transport rule to use the connector if the recipient domain is specific domain. But as we decided to use Exchange online outgoing emails thru Microsoft, I would like to know the best practice to Thanks in advance for your help.