dhananjay wrote:
When you say .. no body and no header ... does it mean that ... "." can
appear in header part like in following example.
>>DATA
<<354 start data; end with <cr><lf>.<cr><lf>
Subject: -ve testing
. To: a(_at_)test(_dot_)com <mailto:a(_at_)test(_dot_)com>
In SMTP DATA, a '.' at the beginning of a line in the data to be transferred
must be preceded by another '.'. See RFC 2821 section 4.5.2. A '.' at the
beginning of a line which is not followed by another '.' or by CRLF is not
permitted.
In such case, such message should be treated as illegal .. is that
correct ?
First let's distinguish between the SMTP protocol as discussed in RFC 2821
and the message format discussed in RFC 2822. SMTP is a means of transferring
some ASCII data from one system to another. That data is conventionally a
message as defined in RFC 2822 -- while in theory any ASCII data could be
transferred, if it's not a message conforming to RFC 2822 it will not be
likely to be recognized as a message by the recipient. Note that there is a
division of responsibility; the data is transferred by software implementing
the SMTP protocol -- such software is known as a Mail Transfer Agent (MTA).
The message is generated and displayed by different software, a Mail User Agent
(MUA). An MTA is not supposed to care about the message content (see RFC 2821
section 2.4).
That sequence is not legal because it does not comply with RFC 1123 section
5.2.11.
Such a sequence can never arise between conforming SMTP implementations.
It's also not valid message (RFC 2822) content.
"." cant be accounted for anything, as ". To" can not be considered as a
valid optional header field since header field name must not contain <sp>.
Prior to RFC 822, a header field name could theoretically contain spaces, but
no such header field was ever formally defined, and the current syntax does
not permit spaces in a header field name.