POP, IMAP and NNTP are also plain text protocols. What's interesting about SMTP as well as NNTP is that the data phase in the former as well as the post phase

POP, IMAP and NNTP are also plain text protocols. What's interesting about SMTP as well as NNTP is that the data phase in the former as well as the post phase in the latter allow for all ascii characters to be transmitted as is without any issue other than NUL. The period needs to be escaped in certain cases such that a CRLF.CRLF doesn't prematurely end the data phase or article post. Clients actually emply "dot-stuffing" to address that case, meaning that any line that starts with a period is modified such that it starts with 2 periods before being transmitted to the server. When a client receives the email or article, it will remove the extra period so that the lines start with a single period.