SMTP dot stuffing.. when and where to do it?

transilvlad picture transilvlad · Mar 5, 2013 · Viewed 9.9k times · Source

I have found conflicting information about dot stuffing when transmitting an email.

  1. stuff a dot if the line contains a single dot (to avoid premature termination)
  2. stuff a dot to every line stat starts with a dot
  3. stuff a dot to (1) and to every line part of a quoted-printable message part only

Can anyone clarify?

Answer

chus picture chus · Apr 16, 2013

According to the SMTP standard RFC 5321, section 4.5.2:

http://tools.ietf.org/html/rfc5321#section-4.5.2

To allow all user composed text to be transmitted transparently, the following procedures are used:

  • Before sending a line of mail text, the SMTP client checks the first character of the line. If it is a period, one additional period is inserted at the beginning of the line.
  • When a line of mail text is received by the SMTP server, it checks the line. If the line is composed of a single period, it is treated as the end of mail indicator. If the first character is a period and there are other characters on the line, the first character is deleted.

So, from the three points of your question, the second one is right.