
Hi @DS-09011323-0
Dynamics 365 Server-Side Synchronization processes emails based on the folder they reside in within Exchange/Outlook.
The user mentions the email "arrives back in the user's Outlook mailbox." This indicates that a copy of the sent email is landing in the user's Inbox. When Dynamics detects this email in the Inbox, it treats it as a new "Incoming" message from the sender (even if the sender is the user themselves), creating a duplicate.
You need to prevent the sent email from landing in the Inbox. Check the following:
1. Remove "Self" from Recipient Fields (Most Likely Cause)
Check if the user is including their own email address in the To, CC, or BCC fields when sending the email from the CRM form.
2. Check Outlook Rules
The user may have an Outlook rule that automatically moves or copies sent messages to the Inbox.
Fix: Review Outlook rules and disable any that route sent emails back to the Inbox.
3. Verify System Settings
In rare cases involving internal emails, a specific setting can cause duplication.
Hope this helps