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smtp

How can we send dot in smtp protocol

If we want when using the SMTP protocol, inside the text a

\n

.

\n

What should we do so that it is not confused with the endpoint of the email in the SMTP protocol?

Solution

  • The RFC has a separate section about the escape mechanism for sending a lone dot on a line; it's colloquially called "dot stuffing".

    In brief, any leading dot on a line needs to be escaped with another dot. So, to send a line containing one literal dot, you'd send

    ..

    and to send a line containing two literal dots, you'd send

    ...

    etc, with the usual <CRLF> line terminators required by the protocol (your example seems to incorrectly assume just <LF> which is often tolerated in practice, but technically not correct). The receiving server correspondingly strips any initial dot from each line of the data.

    The RFC refers to this mechanism as "transparency"; RFC 5321 section 4.5.2