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How do I configure outMail as a send connector in Office365?
How do I configure outMail as a send connector in Hosted MS Exchange 365?
How do I configure outMail as a send connector in Microsoft 365?
How do I configure outMail365?


Follow the guide below to configure outMail as a send connector for Microsoft's hosted exchange 365 / office 365.

It is assumed you already have the following :-

  • A working office365 environment
  • An active outMail service

Outmail365 allows you to use an existing Outmail account to send out email from your own domains on Microsoft365/Office365 hosted Exchange.

In order to use Outmail365 - you need to add your sending domain to the Outmail account under Outmail365 settings, and then configure your Microsoft365/Office365 Exchange to use the information provided. Outbound email will then go out via your selected Outmail account - providing you with the easy visibility and log tracking that Outmail provides.

Step 1 - Add your domain as an Outmail365 domain

First we will add your domain(s) to the Outmail account in order to allow us to associate outbound email with the correct account.

You will need:

  • An existing Outmail account
  • Access and ability to amend the DNS records for any domains you wish to use.

Goto the settings page of your existing Outmail account and click the +Outmail365 Domain button:

outMail Settings panel, click button "Add Outmail365 Domain"

Enter the domain from which you'll be sending email. Note You will need to be able to amend the DNS records for this domain in order to verify ownership:

outMail Settings panel, adding domain name used in 365

The record will be created and the details of the DNS TXT record that is required will be displayed.

outMail Settings, shows the DNS TXT record that needs to be added to the domains DNS for ownership verification

At this stage you will need to login into the DNS control panel for your domain.

Login to your domain's DNS control panel and add the TXT record to the top level of the domain.  We can't show examples of this stage because there are so many DNS control panels, we simple couldn't cover them all.

Pointing Finger with speech saying, "Need a Send Connector for Exchange, Keep scrolling down"

Once the DNS changes have been made and rippled out an example output from the Unix command dig shows the TXT record as it should appear:

Example of dig results for a DNS TXT record

Once you have created the DNS record, you can click the ReCheck button to tell the system to verify your domain.

If you need to return to this screen later, you can return to the Outmail Settings page for your account, and you will see any domain(s) awaiting verification:

outMail Settings domain awaiting verification

Click on the Edit button and then click on the Verify button to return to the DNS verification page:

outMail Settings verifiy the domain name

Once the required TXT record has been created and is visible to the server, the list of domains, will show Verified and will provide a Outmail365id Header Value. This Header must be inserted into email being sent by your Microsoft365/Office365 Exchange server in order to allow Outmail to verify and identify outbound email from your domain.

Copy the Outmail365id Header Value as you will need it when you configure Exchange

outMail Settings, outmail365 header value

Step 2 - Creating the Connector in Office365

We will now create a Send Connector on your Microsoft Tenant to direct outbound email through your Outmail account.

You will need:

  • Complete Step 1 above
  • Global or Exchange admin rights to your Microsoft365/Office365 tenant

Login to your Microsoft365/Office365 Tenant at and open the Admin tool:

Microsoft 365 Main Admin Menu

You will need to expand the menu using Show all to access the admin tools:

Microsoft 365 Admin Center Menu

Click the Exchange admin tool:

Microsoft 365 exhange menu

Once it has opened, click the Mail flow menu to expand it, and then click Connectors:

Microsoft 365 exhange menu, select the mail flow menu, then Connectors option

IMPORTANT NOTE: If you already have a Send Connector with the address space set to '*', you will need to temporarily disable it to allow the new Send Connector to be used during the (mandatory) validation process  later on.

 Click the + Add a connector button;

Microsoft 365 Exhange Connectors, add a connector

In the New connector panel, select Connection from Office365 and Connection to Partner organisation, then click Next:

Microsoft 365 Exchange, Send Connector, Connection from Office 365

Enter a name for the connector (e.g. Outmail365) and add any description to explain its use, then click Next:

Microsoft 365 Exchange, Send Connector Name

Assuming all your outbound email will be going via Outmail, enter * into the domains box, and click the + to add it to the list, then click Next:

Microsoft 365 Exhange Send Connector Scope

Select to send through the smart host, and enter and click + to add it to the list, then click Next:

Microsoft 365 Exhange Send Connector, Set routing to go via outMail (outmail365)

On the Security Restrictions page, leave all settings as default (pictured) and click Next:

Microsoft 365 Exhange Send Connector Security Restrictions

Enter a valid, but external email address in order to allow the system to generate a test - click the + to add it to the list. Once it's in the list, click the Validate button:

Microsoft 365 Exhange Send Connector Validation Email

The page will show a Validating progress spinner, and then finally show that the validation was successful. Once it has completed, click Next:

If validation fails please see the section below labelled "Problem Solving"

Microsoft 365 Exhange Send Connector Email Validation Successful

Check all the items on the Review Connector page look correct, and click 'Create connector':

Microsoft 365 Exhange Send Connector Review

Step 3 - Create Rule to identify email with your Outmail account

You will need:

  • Complete steps 1 and 2
  • The Outmail365id Header Value from your Outmail Account configured in Step 1

Return to the Exchange Admin tool if you aren't already there, and click the Rules menu

Microsoft 365 Exhange Mail Flow Menu, Select Rules

Click on the + to add a rule and click Create a new rule... to add a custom rule:

Microsoft 365 Exhange Mail Flow, Create a new rule

Provide an appropriate name for the rule (e.g. Outmail365) and select The recipient is located... by clicking the drop-down arrow. Select Outside the organization in the pop-up box and click OK:

Microsoft 365 Exhange Mail Flow New Rule Name

Back in the new rule window, click the More options... to allow us to access the necessary options. The page will update:

Microsoft 365 Exhange Mail Flow Rules, more options

Once the page has updated, you can click on the drop-down arrow on Do the following... and select Modify the message properties... and then set a message header:

Microsoft 365 Exhange Mail Flow, modify message properties and set a message header

Once you have chosen to set a message header, click on the first Enter text... link:

Microsoft 365 Exhange Mail Flow Rules Enter Header Text Menu

In the message header box enter X-Outmail365id - this is not case-sensitive - and click OK:

Microsoft 365 Exhange Mail Flow Rules Set Header Text as X-Outmail365id

Back in the new rule window, click the second Enter text... link:

Microsoft 365 Exhange Mail Flow Rules select the enter text menu

In the header value box paste the Outmail365id Header Value that you were given in Step 1, and click OK:

Microsoft 365 Exhange Mail Flow Rules, set the header value

The new rule page should now contain the fields as shown (with your own ID in it), now click Save:

Microsoft 365 Exhange Mail Flow Save new rule

The completed Rule will appear in the rule list, and the correct information should appear in the side panel:

Microsoft 365 Exhange Mail Flow Rules List


You have successfully set up your Microsoft365/Office365 account to send out via Outmail. Any email will appear in the logs and statistics as usual.


Problem Solving

Below is a list of common gotchas.

Validation Failed

After you click the validate button you see a failure message similar to below, but you receive the test email.

microsoft 365 exchange mail flow rules validation failed

Usually when validating the send connector at this stage we don't expect you to receive the validate email.  The fact you did however receive the validate message but validation failed typically means you already have a different send connector already setup with a scope of "*".

You will either need to disable the first send connector or change it's scope before trying to create the outMail365 send connector.



Looking for a send connector for Microsoft 365?

outMail is an outbound SMTP send connector you can rely on, with great customer satisfaction.

  • Microsoft Hosted Exchange (Microsoft 365)
  • Secure SMTP Send Connector
  • Support for SPF & DKIM
  • Easy setup

What are you waiting for? Give it a try today.

Uninstalling / Removing outMail365

To prevent mail flow from Microsoft 365 Exchange to outMail you need to complete the following

  • Remove the Send Connector created for outMail365
  • Remove the Mail Flow Rule which contains the header rule
  • Remove the domain information from the outMail Settings
  • Cancel your outMail service if you're not using it for any other forms of sending emails


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