The enterprise has been tasked with creating a corporate email for all staff members in the format of name@company.com. Whilst I would prefer to utilize a local free mail server, there are frequent power outages and occasional internet instability which make this difficult. As a result, we have identified a few key boxes (such as director and marketing) that require 100% deliverability.

 I propose that these boxes should be serviced by Google mail. However, it would be costly to migrate all mailboxes (of which there are over 50) to this service. Therefore, my question is whether it is possible to have some mailboxes connected to the @company.com domain served by a reliable, paid email hosting service, whilst less important mailboxes are serviced by our internal mail server.

It seems to me that in your specific case, implementing split delivery would be beneficial. This functionality essentially allows Gmail to receive all incoming mail, and any messages addressed to existing mailboxes will be kept within Gmail while those that are not recognized will be forwarded to your own server. However, it's worth noting that the availability of this option may depend on your Gmail tariff plan.
Additionally, it's important to carefully consider the configuration of your mail DNS records in order to ensure that you can both send and receive mail through both Gmail and your self-hosted server.

When it comes to managing email for an organization, finding an efficient and effective system is crucial. In addition to split delivery, there are other tactics that can be used to help keep email flowing smoothly. For example, implementing filters and labels can help to keep email organized, while using templates for commonly-sent messages can save time and effort. Taking the time to explore different options and customize settings to meet your specific needs can make a big difference in the long run.

An MX record is created for a mail domain, that is part of the address after the @. It does not allow you to divide servers by mailbox name.
You can only separate mails by domain, separately abc@company.com and separately bcd@mail.company.com.
@ IN MX 10 own.company.com
mail IN MX 10 external.company.com

P.S. oh yes, i forgot the answer to your question.
You can have two (or more) MX records for one mails domain and different mailservices, but their purpose is totally different and you will not use them for your scheme.
There are services that allow you to host all the mailboxes of your organization on a reliable mail hosting service. The cost should please your accounting department.

Routing mail through a single NAT gateway to multiple servers based on the recipient's domain is not possible because the gateway lacks knowledge of the SMTP protocol. One workaround could be installing a mail server on the gateway to redirect incoming mail, but this solution may be hardware or operating system-dependent.

Instead, it may be more effective to focus on understanding mail routing directly on the mail web server. To better understand your situation, could you provide more detail about whether you plan on creating a new AD forest or utilizing an existing one? The answer to this question will impact how the transition from your old server to the new one is handled. It's also worth noting that Exchange Server can only support one organization per forest, so it's important to take this into consideration when planning any migrations or changes to your email infrastructure.

Managing email infrastructure can be a complex process, particularly when dealing with multiple servers and network configurations. It's important to have a solid understanding of the underlying technologies and protocols in order to make informed decisions that will keep your system running smoothly. Additionally, implementing regular backups and testing disaster recovery plans can help to minimize disruptions in the event of unexpected issues or downtime.

Yes, that is possible. This is known as a split delivery email setup.

In a split delivery setup, you can designate Google Workspace (previously G-Suite) as your primary mail server and your local mail server as a secondary one.

Here's an outline of how it works:

A message that is sent to any account with your "@company.com" domain first reaches Google's servers.

If the recipient's address is in your Google Workspace, Google delivers the message only to that inbox, and the process is done.

If the recipient's address is not found in Google Workspace, Google passes the message on to your local mail server (secondary server).

The local mail server then delivers the message to the appropriate inbox.

This approach ensures deliverability for the primary mailboxes since Google servers are highly reliable. The remainder of the traffic is routed to your local server, minimizing cost.

To configure this setup, you'll have to set up your domain with Google, create your important mailboxes, configure the MX (Mail eXchanger) records (which are records in the Domain Name System that specify a mail server responsible for accepting email messages on behalf of a recipient's domain), then set up routing rules inside Google Workspace to enable split delivery.

As an additional note, Google's email service is not the only option for hosting those primary mailboxes. Microsoft 365 is another popular choice for businesses, and they also support similar split delivery configurations.


If you're looking for more detailed steps on how you can implement this setup, here is an outline:

Note: This involves technical concepts and might require the help of a person skilled in IT if you're not comfortable with those.

Set Up Google Workspace Account

First, you would need to go to the Google Workspace website and create an account for your domain (company.com). During the process, verify your domain and set up your primary mailboxes, those are the ones that require higher reliability.

Configure MX Records

To start receiving emails in Google Workspace, you'll need to change the MX (Mail Exchanger) records of your domain to point to Google server. This is typically done where your domain name is registered or managed.

MX records for Google might look similar to these:

ASPMX.L.GOOGLE.COM
ALT1.ASPMX.L.GOOGLE.COM
ALT2.ASPMX.L.GOOGLE.COM
ALT3.ASPMX.L.GOOGLE.COM
ALT4.ASPMX.L.GOOGLE.COM
Prioritize these records properly according to Google's guidelines.

Configure Split Delivery

This is where you set up what happens if Google Workspace doesn't recognize an email address. Within the Google Admin console, you'll need to navigate to the routing settings and create a new routing rule.

Specify that if the recipient is unrecognized, the message should be sent to your local server. You'll need to provide the server's IP address or hostname.

Setup Local Email Server

Lastly, make sure your local email server is set to receive emails from Google's servers and properly distribute them to the secondary mailboxes, ensuring that the server would understand that it's responsible for managing emails for the secondary mailboxes (those not set up in Google Suite).

Test

Send test emails to check everything is working perfectly. Make sure emails sent to both primary and secondary addresses are being delivered correctly.


You can make two or more MX entries for one domain name and two (or more) mail services. This is not only for backup purposes (where, if the primary mail server is down, the mail will be delivered to the secondary server), but can indeed be used to spread the mail traffic across several mail servers, as you might be planning.

Assuming your Google Workspace is your primary mail server, the MX record of the Google server would have a lower preference number (which indicates higher priority in the MX setup). For the other server that you are running locally, you would then set a higher preference number (lower priority).

@  MX  1  aspmx.l.google.com.
@  MX  5  mail.yourlocalserver.com.
In the example above, the number is the priority. The lower the number, the higher the priority.

It's important to note though, in this setup, if the Google server is reachable, the emails will only be delivered there. The local server will only get emails if Google's servers are down.

In order for some mailboxes to be delivered to the local server and others to Google Workspace, you need to configure the delivery management within Google Workspace (for unrecognized mailboxes) and on your local server (for everything else), as I outlined in the previous answer.

Remember, also, to properly configure SPF, DKIM, and DMARC records and settings for both servers to help protect from spoofing and ensure optimal mail delivery rates. These records are managed in your DNS and server settings. You should obtain instructions for this from Google Workspace for their side and from the documentation for your local server system.

Using multiple mail servers like this requires careful administration to avoid missed emails or other issues. Always test thoroughly before transitioning to a new email setup.

Yes, you can! Configure two MX entries for one domain to use two different mail services simultaneously. Prioritize entries based on preference to ensure seamless email routing. This allows flexibility and redundancy, ensuring reliable mail delivery even if one service encounters issues. Optimize your domain's email management effortlessly. 📧✨