OK, if they're the only 2 options I'll try them. I briefly looked at saving the text of the mails, but there didn't seem to be any way to copy the text, i.e. I couldn't select the text to copy it to my PC's clipboard. I'll try it again later today.General answer: The age or any "outdated" tag does not say if they work or not! Just ignore that and read the addon comments first at www.esoui.com e.g. If addons do not work you can read that by 90% chance there directly!
Else: You need to simply install and tests that.
Postmaster just works fine for me, since ages.
If they say they can save the mails, try it.
I cannot say if MailR still works with the mail saving but just try it.
All they can do is save that to you SavedVariables files (read here what that is and wher to find them for your addon in question: https://www.esoui.com/forums/showthread.php?t=9235 )
and you need to backup that SavedVariables file then or openit with a text editor and copy the text.
But before you do that complicated workaround: Why not simply saving a screenshot then or copy the text from the mail to a notepad txt file?
Less effort, same result in the end.
I think MailR (in the past years ago) showed you an own UI ingame for saved mails, so that would be a benefit if it's still available and working.
Thanks for the suggestion, but this doesn't work. For now, I just screendumped it (twice, because not all of this particular mail is visible without scrolling). The one I wanted to save, by the way, is a system mail, not a user mail, if that makes any difference.Click into email text, press CTRL+A to select all then CTRL+C to copy to clipboard like in every windows program and then CTRL+V in your text editor to paste it.