Unable to save emails WITH ATTACHMENTS
I need to save off a large number of emails with their attachments from the native Mail program. The emails and attachments are resident on the iMac (that is, I can open the emails and can open their attachments without being connected to the source server). I have tried multiple ways to do this but can only save the emails (in some cases) but never with attachments. I must save them OFF this computer to retire or repurpose this older iMac.
I am aware I can save the attachemnts individually, but there are a thousand or more emails so I must automate this process. I need to have the attachments with their source emails. This is an older computer and an important document preservation effort involving my late father-in-law's professional work.
iMac 21.5" Late 2013, Catalina 10.15.7 - this is up-to-date for this system. This iMac is not Big Sur eligible.
Here are all the things I have tried and the results:
Drag and Drop: When I drag an email to a folder in Finder, a tiny envelope icon appears as I drag it across Mail. When I get to the folder, the envelop turns into the normal large green plus icon. Then when I release the message on the folder, nothing happens - absolutely nothing. No email is saved with or without the attachment. No error or other message is issued. Just nothing. (I have tried this on a MacBook Pro and it works just fine.) Incidentally, if I drag and drop the attachment to Desktop or the folder, it saves the attachment correctly.
Export (or Print) as PDF: This creates a nice PDF of the email but it only contains an icon of the attachment, which cannot be opened.
File - Save As - Raw Message Source: This creates an .eml file with 0KB. When opened, the sender states No Sender and the subject line states (No Subject). There is not content whatsoever, and of course no attachment.
File - Save As - Rich Text Format - Include Attachments: This creates an .rtfd file with a small KB size. When opened, it contains the From, To, Date and Subject information as well as the content in text. But it does not contain attachments.
File - Save As - Plain Text Format - Include Attachments: This also creates an .rtfd file with a slightly smaller KB size. When opened, it contains the From, To, Date and Subject information as well as the content in text. But it does not contain attachments.
Please let me know of any suggestions on how to save off these emails with attachments. Thank you!
iMac Line (2012 and Later)