DataLines final class

A message cut into the lines SMTP DATA sends. Any line break (CRLF, CR or LF) ends a line. A line longer than 998 characters is cut at its last space within the first 998 (the space dropped), or at 997 when there is none; in the header block (when the first line reads "Name: ..." with no space in the name, up to the first empty line) each continuation starts with a tab. Dot stuffing is the sender's job, after the cut.