Email attachments are now also covered by the Office Graph and Delve
Since a couple of days Delve is showing Email attachment:
More details about this, the Delve card for “Emails with Attachments” and its functions can be found in this blogpost: Delve starts to add emails with attachments to results
Using the REST API we can get this data, too. Getting all emails with attachments for the signed in user we can use this call:
The contentcalass filter 'contentclass:exchangeattachment’ is scoping the result only to mails with attachments.
This query only returns result for the user who runs the query. Because of Email contentclass results are only shown in the Home Feet in Delve it is a private signal. In Detail every person who received the mail and within the mail also the attachment gets it in his Delve Home Feet: