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Select the Reply/Forward/Print icon, use two fingers to zoom in on the document, and use the share button from there to send to Notes.
 
ok thx... actually all that did was send it to notes as .pdf.. I really only needed the text.

I found just selecting text in email and "share" on popup does it fine.
 
Unfortunately you have to have iCloud Notes enabled or you can no longer share *into* Notes from another app.
 
I think OP does have iCloud Notes on, just that they were looking at an Apple support note on how to send a text file/text file attachment to Notes vs wanting to send the text of an email to Notes.

But, they did find a workaround re: do a select all text and then send that to Notes.

The whole send to Notes share sheet does seem to be app dependent. But also make sense re: content/source type. For example, I can send this forum page to Notes, but it will take the link vs actual text (some sense: URL content is/can be dynamic; can always generate a PDF and send that to capture as-is at that time). Emails, loaded with images, tables, header information, so, lots of extra stuff that maybe makes more sense to share as a PDF (as noted by OP). Did a quick test of what the support notes says, and it still works: created an email with an attached .txt and .rtf file, both were sent to Notes as the full documents.
 
It's ridiculous that you could share into IMAP-hosted Notes *before* iCloud Notes became a thing, but since, you can't. IMAP certainly hasn't changed in the meantime.
 
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