Ability to render attachment within the attachment in email messages

[usman-aziz]

This feature is requested in the forum topic: https://forum.groupdocs.com/t/attachments-within-attachments/6199

The user has requested the ability to display all the attachments (attachments within the attachments) recursively.
For example, Email A has attachments B and C - B is an email with attachments B1 and B2. The viewer should have the ability to show pages of Email A (email body), B (email body), B1 (attachment to B), B2 (attachment to B) and C in that order.