Office 365 (Outlook) - How are Multiple Attachments Saved?
How to save multiple attachments in Outlook via the client or web.
In a message with multiple attachments, click on an attachment to open the Attachments tab in the ribbon.
Select Save All Attachments, this will open a new window.
NOTE: All attachments are highlighted by default, if you do not want all of them you can select them individually while holding the CTRL key.
This will open the Explorer window.
Browse to the folder you want to save them to and click OK.
Attachments are saved as individual files.
Outlook via theWeb
Select the message with the attachments and click Download all
All the attachments are downloaded as a zip file to your default download file location.(usually a folder named "Downloads")
NOTE: The file's name is the subject of the message.