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A++ Quick, accurate and to the point. &nbsp; Thanks so much!!
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A++ Quick, accurate and to the point.   Thanks so much!!

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Currently 1000 users reside on our Zimbra mail server. &nbsp;We have stood up our exchange environment and have been doing some migrations from Zimbra to Exchange. &nbsp;Currently all mail-flow goes through a mail gateway then to our Zimbra server and then if the mailbox is not there it moves onto Exchange. &nbsp;My only problem is that the users that have been migrated to Exchange may need to send email to users that are still on the Zimbra server. &nbsp;There could be a JSmith@domain.com on Zimbra and Tjohnson@domain.com on exchange wants to email him. &nbsp;Since they are identical domains and JSMITH is not on exchange yet the delivery fails because there is no mailbox on exchange. &nbsp;I have played with the send connector to try and route all mail through our mail gateway but Exchange keeps being the master and giving delivery failures. &nbsp;Is there any way to tell exchange that if an e-mail does not exist to route to a different gateway and not do an NDR?
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Currently 1000 users reside on our Zimbra mail server.  We have stood up our exchange environment and have been doing some migrations from Zimbra to Exchange.  Currently all mail-flow goes through a mail gateway then to our Zimbra server and then if the mailbox is not there it moves onto Exchange.  My only problem is that the users that have been migrated to Exchange may need to send email to users that are still on the Zimbra server.  There could be a JSmith@domain.com on Zimbra and Tjohnson@domain.com on exchange wants to email him.  Since they are identical domains and JSMITH is not on exchange yet the delivery fails because there is no mailbox on exchange.  I have played with the send connector to try and route all mail through our mail gateway but Exchange keeps being the master and giving delivery failures.  Is there any way to tell exchange that if an e-mail does not exist to route to a different gateway and not do an NDR?

Migrating from Zimbra to Exchange 2016 mail flow issue

Exchange is the server side of a collaborative application product that is part of the Microsoft Server infrastructure. Exchange's major features include email, calendaring, contacts and tasks, support for mobile and web-based access to information, and support for data storage.