Maybe because this is from December 2014 is why I don't understand it... I've tried importing the Suggested.enex into my Evernote for Mac and all the note contains is a Note Title of 'Test' and the word 'Test' in the body—it isn't a link of any kind. I also imported the 'current.enex' file and I see the same 'test' text in the Title and Body of the note, but this time there is also a link above the word 'Test'. The link is also the word 'Test', but when editing the link, it has a destination of: airmail://message?mail=jbr%40humppa.dk&messageid=etPan.544e3893.43bc62e9.3bba%40tiny.lan which I assume is possibly to a message in the OP's Airmail account.
The suggestion states to use 'note links' for the link back to the e-mail message. I was an Evernote user back in 2014 and my understanding of 'note links' has always been a way to create links to other Evernote notes, but not links to something/anything outside of Evernote, which is what is being discussed here...a link back to the e-mail message in Airmail. So my understanding is the only way it can be done is using a standard hyperlink.
I don't know if the OP is wanting the link to be the e-mail Subject text that is hyperlinked to the e-mail in Airmail versus the current text of 'Open in Airmail'...? I'm not sure using the e-mail's 'Subject' would make anything more clear, tho... Maybe instead, text of: Open Original E-Mail in Airmail OR Open original message in Airmail. Options being 'e-mail' or 'message' and title case or sentence case.
Having said all of that, I would say this is probably a much lower priority than a number of other items. Although, if changing the current text that is used would improve some confusion I am unaware of, I assume that would be easy to do...
If the standard Evernote Share Sheet is used, it provides options to change the resulting Note Title, add additional text that will be placed in the body of the Note, select the Notebook, and select Tags. However, the standard Evernote Share Sheet needs to be improved in the following ways: 1) Only place in the Note Title field, the text prior to the first <return>. The rest of the text that is added should ONLY go into the Body of the Note versus the Title AND the Body. 2) Allow us to ADD tags, not such select from those that exist. It would also be helpful if you could do a Search when selecting Tags versus having to scroll or tap the A-Z letter.
I’ve also read a few comments in this Airmail Feedback area about attachments not being included when sending to Evernote. I haven’t tried this yet to determine if the comments were old or if this is still an issue, but any attachments to the message should definitely also be sent along with the message.
I do want to say that I REALLY like the full header information that ends up in Evernote when using the current ‘Send to Evernote’ action, along with the ability to open the message in Airmail, which facilitates responding to the message or forwarding, if either is necessary.
I agree with the suggestion to further improve the ‘Services’, or integrations, and with Evernote in particular. I actually just started trying out Airmail and I’m liking most everything so far, but when choosing ‘Send to Evernote’, nothing happens, no option to select the Notebook, Tags, edit the Title, or add additional content that will end up in the body of the note, and not even an acknowledgement. So I assumed it wasn’t working, until I went into Evernote and saw 5+ copies of the message I had been trying to send to Evernote! The standard Evernote Share Sheet allows for all of these additional options, as well as an acknowledgement..
In addition, a comment about the OP’s suggestion of an ‘Add to Evernote and Archive’ button. PLEASE, whenever you consider anything related to ‘Archive’, also do the same for ‘Move’ (to folder). There are two camps of e-mail users—one archives and the other moves to folders. I am of the second camp. I rarely ever archive anything. Instead, I file (move) every message I keep to a folder.