Once in a while, I'm drafting e-mails in an orgmode buffer. I'd like to export the plain text, but without wrapped lines. Usually I forget to disable auto-fill-mode while writing.
So after finishing the text, I copy it into scratch, mark it and then:
M-x replace-string Ctrl-q Ctrl-j Ctrl-q Ctrl-j RET XXXX RET. Result: Every new paragraph is replaced by XXXX.
Next step:
M-x replace-string Ctrl-q Ctrl-j RET <space> RET : I'm replacing the single newlines with a singel space.
Next step:
M-x replace-string XXX RET Ctrl-q Ctrl-j RET : I'm replacing the XXXX against the former new paragraphs.
Ready for copy and paste.
#Edit:#
After OP made a comment about the #+OPTIONS:, I found that you can write #+OPTIONS: \n:nil into the preamble of the org file, which is supposed to toggle whether to preserve line breaks (`org-export-preserve-breaks').
Unfortunately, this works in export to html, but not in export to plain text.