Issue
Some of your campaigns are being flagged as duplicates in Inbox Monitor. 

Common scenarios
There are several reasons why campaigns are being registered as duplicate emails in Inbox Monitor:

• Your system may be sending duplicate emails
• A mailbox provider may be delivering duplicate emails to your subscribers' inboxes
• You need to implement a Matching ID

Troubleshooting
To identify the cause of the problem:

1. Navigate to the affected campaign's Campaign Details page in Inbox Monitor
2. Scroll to the bottom of the page to locate Reference Accounts
3. Select Details next to one of the accounts
4. Select the Msg Headers icon to view the message source
5. Look at the Received: portion of the email header. This details the hops that your message took on its way to its final destination. Each of these hops has a time stamp.
6. Review the time stamps.

If the time stamps on the original and duplicate messages are different then your system sent duplicates. If your mailing often stops and has to be restarted, you may see this result since there may be overlapping mail being sent from your system. If the time stamps are the same then the mailbox provider may have delivered the same message twice. This often happens when a mailbox provider network is being flooded by network traffic due to a virus attack. No action is required on your part.