Migrate Zimbra to Exchange Online

New Contributor

Hi all,
Im going to migrate Zimbra to Office 365. So have to configure mail flow coexisting between Office and Zimbra for user in 2 email system can send message to each other.

Both of Zimbra and Office 365 using the same smtp domain like abc@mydomain.com. And the MX record pointed to Zimbra

1/ At the Zimbra i was configure forwarding in each mailbox for forward message from Zimbra to mailbox in Office 365 -> Its Worked
2/ In the Office 365 i was created a internal relay connector to Zimbra server -> Stuck.

So the issue is when sender from Office 365 to sending a message to recipient in Zimbra. The message status was delivered but when i trace message in Office 365, but after that i receive that
" mail.mydomain.com rejected your message to the following email addresses:

recipient@mydomain.com (recipient@mydomain.com)
Your message was rejected by the recipient email server. Please check the recipient's email address and try resending your message, or contact the recipient directly. For more tips to help resolve this issue, see DSN code 5.1.0 in Exchange Online - Office 365. If the problem continues, contact your email admin.

mail.mydomain.com gave this error:
<sender@mydomain.com>: Sender address rejected: mydomain.com"


So guys please help me to resolve this issue. I don't know why Zimbra is rejected the message. Should i do any action ? Thanks a lot ^^

3 Replies
Zimbra is believing that you are spoofing the domain name, so you would need to ask them to allow emails originating from Office 365 to be permitted senders.

Hi @tutrieu 

I read your query and I suggest  you the best solution to your problem is use of professional tool. You can use any third party tool available in the market to migrate your Zimbra mails to Exchange online. The professional tool named Zimbra Email Migration software can migrate all your Zimbra mailboxes without facing any difficulties. You can use this professional tool as per your needs.

Hi Tutrieu have you add this section "include:spf.protection.outlook.com" in the SPF record of your domain ?