in reply to Encoding horridness revisited: What's going on here? [SOLVED]
I had a similar issue. I was trying to send a plain text email from Linux. I tried various Perl modules, mail, sendmail, etc. I then realized that Outlook was formatting my email. If you use Outlook 2016 open one of your test emails, go under file, properties and look at the header information. You should see something like this: Content-Type: text/html; charset="ISO-8859-1". If you find that the encoding is correct, then you need to check to see what Outlook is doing with your email. On your Outlook screen under file, options, mail you will see a button for stationary and fonts. The select the font button for composind and reading plain text messages and make sure that it is set to courier new and whatever font size you like. Then try opening one of you plain text emails and see if your white space formatting is OK.