I'm also glad that Notepad worked for you. Copying and pasting from email into RM has been a long term problem for me because I frequently see the exact same problems you describe.
I don't like Web browser based user interfaces for email, so I use a Hotmail account and a Gmail account with an IMAP client on my Windows desktop. For me at least, this provides a much better experience than using the same accounts on the Web. My present IMAP client of choice is Mozilla Thunderbird, which is free.
Copy and paste from Thunderbird into RM has the same problems you describe. But Thunderbird has a View Source option which I use only when copying and pasting into RM and which provides a "very plain text" view of the email which works without having to use Notepad as an intermediary to clean up the white space. I have to copy and paste twice, once for the headers and once for the body of the email. I do the copy and paste of the headers separately because Thunderbird's View Source option shows all the very voluminous headers - dozens or hundreds of lines of them - when I really only need the basic To:, From:, and Subject: lines.
An additional advantage of the Thunderbird approach is that sometimes Web based email doesn't show you email address, just the sender's name. If all you have after a copy and paste is the person's name and not their email address then it might be impossible later to contact the person based on the information you have pasted into RM. But Thunderbird always shows you both the sender's name and their email address.
Still another advantage of the Thunderbird approach is that it allows me to store the entire email message including attachments as a file in Windows with an EML extension. I can link the EML file into RM as type "File" and I can open it from within RM. When I open it this way within RM, it opens in Thunderbird and I can see all the original formatting and all the original attachments.
Finally, using Thunderbird or other desktop email client means that when I encounter any Web pages with "mailto" tags (email addresses), I can click on the link and it will go straight into Thunderbird to send a message. "mailto" tags don't work when your email is browser based.