Files can stored in Dynamics 365/CRM in emails or against notes. The following entities are used to store the file.
|Entity containing file||Entity where file is stored|
Details of note and the file (if there is one)
|attachment||The file - one copy only|
|activitymimeattachment||References the attachment, if an email with a file is sent multiple times (such as a campaign distribution), then there will be a record for each send.|
A note can only store one file. Therefore, for files stored against notes, there is one annotation record per file.
Attachments cannot be deleted in the user interface, the only way to delete attachments linked to an email is to delete the email.