Don't make it too hard on yourself. Just copy-paste the non-identifying bits of the email, paste it into pastebin.com or a text story here, etc. and make sure not to leak your email address or anything that points to you personally.

Copy-paste is a lot safer than most things. Photos leak something called EXIF data that can contain your GPS (!!!) and even matte surfaces like TVs can have identifiable reflections. Copy-paste is exactly what it looks like: plain text.

Word documents and PDFs all have meta-data in them, too. Granted, MS Paint doesn't really have much metadata in the image files as far as I know, but you could leak info about what OS the screenshot came from or other things on your screen in the image might be identifiable to someone who knew you (e.g. if they can see your desktop background and someone you know remembers it, etc.).

Yeah... computer guys are pretty paranoid about this stuff for good reason. I like plain text and something like pastebin.com. Ctrl-A (select all), Ctrl-C (copy), Ctrl-V (paste), make sure you're posting only the text of the email and not any headers with computer gibberish (that yes, could doxx you) or email addresses, etc., post, done.