I have been using ERPNext for a few years now, and it has never been efficient for me to get my purchase invoices into the system.
I have a dedicated email that gets all these invoices. But I am not sure what kind of Doc should be created with that email and its pdf attachment, to make it practical to create a Purchase Invoice from. I am not looking for auto-populated fields, I am looking for something like a To-Do Doc, which attachments can be made, and the dedicated person for that can be alerted through email.
I remember that there is a To-Do DocType, but It seems that I cannot attach a file to that. It is only a pointer to another Doc, with an explanation.
There are a few doctypes that come preconfigured for this, and you can always make your own.
Create a new custom doctype called “Incoming Purchase Invoice” or something similar, then under the “Email settings” section of the doctype definition make sure that “Allow document creation via Email” is checked. You can then also specify which fields take the subject and sender properties of the email.
The attachment won’t get automatically transferred to the doctype, but it will be attached to the incoming email (and, as a consequence, will be visible and clickable in the timeline). If you want the attachment to get brought to your “Incoming Purchase Invoice” document, you could probably manage that with an event hook (either in an app or a server script).
For notifications, you should be able to use the normal Notification framework to send an email/sms/whatever.