Hi @Kathy Debosschere ,
Welcome to our forum!
Based on my research, i found that the Attachment field is not synced by default. More information: What fields can be synchronized with Outlook?
It's suggested that you could refer to the following article to enable it to sync: Set synchronization direction in Dynamics 365 Customer Engagement (on-premises).
Hope the above help! If it doesn't help, please kindly understand that the Outlook tag here we mainly focus on general issues about Outlook desktop client. In order to better solve your problem, it's suggested that you could post your case in dedicated forum for Dynamics for more professional suggestions. Thanks for your understanding and support!
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