we have been using HostGator as our mail service provider for our domain abc.com, which has 40 users. Recently we acquired 5 M365 business basic licenses. so we disconnected, 5 executive staff from HostGator and created 5 user account in M365 admin center. abc.com domain is added in M365 domain settings but HostGator MX record is still being used in DNS registrar. Now i see, staff are unable to send and receive email between O365 users and HostGator users. but both parties can send to and receive from external domains. which are the configurations need to be done?

You need to set the domain in Exchange Online to "Internal relay", as detailed here: https://learn.microsoft.com/en-us/exchange/mail-flow-best-practices/manage-accepted-domains/manage-accepted-domains#configure-the-domain-type This will ensure that for any recipients that Exchange Online cannot find internally, messages will be routed through the MTA specified by the MX record. Similarly, on HostGator side you need to designate those 5 users as external and configure some form of forwarding to ensure proper message delivery.

How to configure few users in O365 and others in HostGator for a single domain

Accepted answer

Vasil Michev 95,416 Reputation points MVP

2024-03-28T18:08:52.92+00:00

You need to set the domain in Exchange Online to "Internal relay", as detailed here: https://learn.microsoft.com/en-us/exchange/mail-flow-best-practices/manage-accepted-domains/manage-accepted-domains#configure-the-domain-type

This will ensure that for any recipients that Exchange Online cannot find internally, messages will be routed through the MTA specified by the MX record. Similarly, on HostGator side you need to designate those 5 users as external and configure some form of forwarding to ensure proper message delivery.
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R Thayanithy 20 Reputation points

2024-03-29T03:04:36.23+00:00

Thank you. What if i change the MX records to point to O365? will it work? because Hostgator administration is managed by a 3rd party, i dont want to be depend on them.

Vasil Michev 95,416 Reputation points MVP

2024-03-29T07:47:10.48+00:00

At this point changing the MX to point to Exchange Online will prevent you from emailing any user remaining on HostGator, as there will be no way for Exchange Online to know where to route such messages.

Jayce Yang-MSFT 1,246 Reputation points Microsoft Vendor

2024-04-01T08:05:48.5033333+00:00

Agree with Vasil.

If the answer is helpful please click on ACCEPT ANSWER as it could help other members of the Microsoft Q&A community who have similar questions and are looking for solutions.

R Thayanithy 20 Reputation points

2024-04-03T10:11:55.2733333+00:00

Sorry, i was unable to configure this. poor support from our 3rd partly support team. How can we get this done from the O365 side?

will it work if i add O365 MX with priority 0, and HostGator MX with priority 10 ? will the mails be delivered to respective users ?

Vasil Michev 95,416 Reputation points MVP

2024-04-03T12:20:44.9133333+00:00

No it will not. Only the highest priority MX is taken into consideration, you cannot leverage multiple MX records for such scenarios.

R Thayanithy 20 Reputation points

2024-04-03T12:59:06.69+00:00

Thank you. I understand your point. I've added my abc.com tenant to the O365 domain, the TXT record is added, and the domain is verified. However, it still shows as 'incomplete setup' and is forcing me to remove the existing MX and add the O365 MX only to my domain registrar. Please see the screenshot. But could you please tell me how I can get it done if I remove the HostGator MX and add O365 MX only?

Vasil Michev 95,416 Reputation points MVP

2024-04-03T14:24:09.8233333+00:00

Changing the MX will not solve your issue, it just shifts some of the steps. The wizard you are referring to above does not take into consideration scenarios like yours, it's only intended for use where you've moved everything to M365. Just ignore it for now.

If you have already verified the domain, make sure to switch it to Internal relay as advised above. This will allow your O365 users to send messages to HostGator hosted users.

Dilusha Priyantha Karunarathna 21 Reputation points

2024-04-04T02:46:04.3366667+00:00

MX Records Update:

First, ensure that your MX records are correctly configured. Since you’ve already added the abc.com domain to Microsoft 365, you need to update the DNS records in your registrar’s account.

Log in to your DNS hosting provider (where your domain is registered).

Locate the MX record for abc.com and change it to point to Microsoft 365. The correct MX record value should be something like yourdomain-com.mail.protection.outlook.com.

This step ensures that incoming emails are routed correctly to Microsoft 365.

Connector Setup: Set up connectors to enable mail flow between Microsoft 365 and your own email servers (HostGator).
Connectors allow emails to flow in both directions. You can enable mail flow between Microsoft 365 and any SMTP-based email server (like Exchange or third-party servers). In Microsoft 365, connectors route emails based on sender, recipient, content, etc. Refer to the for detailed instructions on setting up connectors. 1. **Local Email Routing**: Ensure that your local email routing is set up correctly. If you have mailboxes in both Microsoft 365 and HostGator, configure local email routing. In Microsoft 365, go to the **Exchange admin center** and create connectors to route mail between Microsoft 365 and your own email servers. This step ensures that emails between Microsoft 365 users and HostGator users are properly routed. 1. **Testing and Monitoring**: After making these changes, test email communication between Microsoft 365 users and HostGator users. Monitor the mail flow to ensure that emails are delivered correctly.

Remember to back up any critical data before making changes to avoid data loss. If you encounter any issues during the process, consider reaching out to Microsoft support or HostGator’s support for assistance.

Dilusha Priyantha Karunarathna 21 Reputation points

2024-04-04T03:03:15.4+00:00

https://learn.microsoft.com/en-us/exchange/mail-flow-best-practices/manage-mail-flow-on-office-365-and-on-prem?source=recommendations
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How to configure few users in O365 and others in HostGator for a single domain

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