Issue
NinjaOne Ticketing creates duplicate tickets or ticket updates when a requester sends a single email to the support email address. You can observe the issue within NinjaOne at Administration → Apps → NinjaOne Ticketing → Email → Email History.
Environment
NinjaOne Ticketing
Cause
A Microsoft Exchange Online change (around September 30, 2026) causes Exchange Online to forward a message a second time after the message returns from Exclaimer or a similar third-party mail signature service. This behavior occurs when you forward email from Microsoft Exchange to NinjaOne Ticketing.
Before the change, Exchange Online recognized the message as already forwarded and skipped the second forward, which it logged as SKIPREDIRECT and ForwardingHandled. After the change, Exchange Online logs REDIRECT and Forwarding SMTP Address and forwards the message again. As a result, two copies of the message reach the NinjaOne Ticketing inbound address.
NinjaOne Ticketing correctly creates a ticket for each email delivery that it receives. This cause is external to NinjaOne Ticketing and outside our control.
Resolution
Exclaimer and customers who applied the following workaround have confirmed that it resolves the issue. The workaround prevents the forwarding mailbox copy from going through Exclaimer, so Exchange Online has nothing to forward a second time.
Workaround: Exclude the Forwarding Mailbox from the Exclaimer Rule
To exclude the forwarding mailbox from the Exclaimer mail flow rule, perform the following steps:
- In the Exchange admin center, navigate to Mail flow → Rules.
- Open the Identify messages to send to Exclaimer Cloud rule.
- In the Except if section, add The recipient → is this person.
- Select the mailbox that has forwarding configured, which is the mailbox whose forwarding setting sends copies to NinjaOne Ticketing. Do not select the ticketing system's address, the contact, or any external address that the mailbox forwards to.
- Click Save.
- Wait at least 5 minutes for the change to apply. The change can take up to an hour.
- Send one internal test email to the forwarding mailbox.
- Verify that NinjaOne Ticketing creates only one ticket for the test email.
This workaround also applies to other third-party mail signature services that use comparable mail flow rules.
Raise a Support Case with Microsoft
Exchange Online logs the second forward after the message returns from the signature service, so Microsoft can confirm why the ForwardingHandled check no longer prevents it. Raise a support case with Microsoft, and include the message traces and a description of this issue in the case.
Additional Resources
To learn more about configuring forwarding addresses for NinjaOne Ticketing, refer to NinjaOne Ticketing: Email and Notification Management.