>
>Not unless RFC821 has been superseded:
>
>     4.5.3.  SIZES
>
>[...]
>
>           text line
>
>                The maximum total length of a text line including the
>                <CRLF> is 1000 characters (but not counting the leading
>                dot duplicated for transparency).

Actually RFC 821 has been pretty much superceded by RFC 2821.  It's a
Proposed Standard right now.  The line length limitation is still the same,
though.

>Oddly, the message format RFC (RFC822) puts no limit on line length.

RFC 822 has also been superceded by RFC 2822, a Proposed Standard.  There
is no mention of line length because the message format can be used with
transport protocols other than SMTP.