Yet another mailto command line tool, rxmailto.cmd v0.1 can so far send one text mail to one receiver via a Mail Submit Agent (MSA) at port 587 supporting SMTP AUTH with CRAM-MD5 and 8bitMIME. That's the minimum I could get away with after the spam flood finally drowned my old mailbox.
Various details are far from perfect, e.g. if a run of words with non-ASCII characters in the subject is longer than 56 octets the subject encoder will emit a folded line longer than 76 characters, and that's not permitted by RFC 2047. On the other hand the script won't break UTF-8 characters in the subject for platforms with UTF-8 as local charset. You get what you pay for, less than 30 KB. ;-)