Jan 04 2019
Feb 28 2020
@ctchidam_123 We are experiencing the same issue, hoping maybe someone will respond if we join your thread!
Jan 18 2021
Ref: Attachment is missing from an e-mail message that is sent to a Microsoft Windows SharePoint Services...
Jun 02 2022
@ctchidam_123 It is an old post but there are several solutions available. See here (mostly Outlook add-ins) and here (SharePoint App).