Non-Delivery Report: [550 5.7.64 TenantAttribution; Relay Access Denied]

1. Log into the Exclaimer portal (portal.exclaimer.com) and Launch your subscription.
   
   
2. Open the Settings menu by selecting the cogwheel icon, then select Mail Flow.
   
   
   
   
3. In the right-hand pane, under Mail Routing Domain, are all the relevant options.
   
   
   
4. In Domain Name, enter the domain where the email should be routed after being processed by Exclaimer.
   We recommend: Use the .onmicrosoft.com domain which can be located in the Domains list in the Microsoft 365 Admin Center: Microsoft 365 Admin Center. This setting is important, and an incorrect domain can result in mail flow issues.
   
   Example:
   
   
   NOTES:
   

   Email is routed back to a mail server identified from the specified domain's MX DNS record.

   To ensure that the email is routed successfully after being processed by Exclaimer, it is necessary to specify a domain with an MX record that points towards a Microsoft Exchange Online server for your organization.

   The MX record for the Domain name (in the Mail Routing Domain settings) should specify a single Exchange Online Server for your Microsoft 365 tenancy.

   To check the MX record for your own Domain name, use a DNS lookup tool, such as MXToolbox.

   Example showing Exclaimer's domain:
   

5. Click SAVE to save your mail routing settings.

If you select Send all email to Exclaimer during configuration, it might be essential for you to, at this stage, to reduce the impact on end-users by ensuring that mail flow is unaffected. To restrict which user's emails are routed to the Exclaimer servers, you can modify the mail flow rule in Exchange Online to only send an email to Exclaimer if the sender is a member of a group in Microsoft 365.

To modify the mail flow rule:

1. Sign in to the Exchange Online admin portal (https://admin.exchange.microsoft.com) as an Administrator.
   
   The Exchange admin center is displayed.
   
   
2. From the left-hand navigation menu, select Mail flow, then select Rules.
   
   
3. In Rules, select the Identify messages to send to Exclaimer rule.
   
   
4. Click Edit rule conditions.
   
   
5. In the Apply this rule if section, click the add button (+).
   
   Example:
   
6. Specify a condition to limit the rule to one or more test users.
   
   For example, The sender is a member of this group
   
7. Click Save.

You will need to allow up to an hour for the changes to take effect.

Sometimes the replication of mail flow settings takes longer than an hour. It may be best to leave the changes replicating for several hours and come back the next day to see if it has succeeded.
We recommend attempting Step 4 - Recreate the mail flow settings after at least one hour has passed since last creating the mail flow settings.

Recreate the mail flow settings to help force the replication to occur:

1. Log in to the Microsoft 365 admin center.
   
   
2. Navigate to Settings > Domains (https://admin.microsoft.com/Adminportal/Home?source=applauncher#/Domains).
   
   
3. Locate and select the domain ending smtp.exclaimer.cloud or smtp.excl.cloud.
   
   
4. Click Remove domain.
   
   
5. Confirm that you want to remove the domain.
   
   
6. Log into your Exclaimer subscription.
   
   
7. From the header bar, select the cogwheel icon to open the Settings menu, then select Mail Flow.
   
   
8. If you have limited the scope of the Exclaimer Mail flow rule to a group as part of step 2 above, then untick Send all email to Exclaimer, then enter the group name in Test Group Name.
   
   NOTE: If you created a new group for this purpose, you would need to start a manual data synchronization before proceeding with these steps.
   
   
9. From the right-hand pane, under Connect to Microsoft 365, click Connect.
   
   
10. Complete the setup as per the instructions here: Apply to email from all devices including mobiles for Microsoft 365 subscription 

Once you have completed the setup, please allow at least one hour.