[Mailman-Developers] EOL handling in Mailman

Mark Sapiro msapiro at value.net
Sat Mar 19 18:59:46 CET 2005

Sylvain Beucler wrote:
>I'm a Savane (gna.org/p/savane) developer, and we noticed that when we
>send mail with newlines in the \r\n format, Mailman converts them to
>I would like to get your point on what we should do to fix the
>problem. I had a look at RFC 822; the EOL (end of line) description is
>not very clear, but it seems that the standard EOL convention is \r\n

RFC 822 is obsolete. The current standards are RFC 2821 SMTP and RFC
2822 Internet Message Format. Both these standards are very clear. For
example RFC 2821 says:

2.3.7 Lines

    SMTP commands and, unless altered by a service extension, message
data, are transmitted in "lines". Lines consist of zero or more data
characters terminated by the sequence ASCII character "CR" (hex value
0D) followed immediately by ASCII character "LF" (hex value 0A). This
termination sequence is denoted as <CRLF> in this document. Conforming
implementations MUST NOT recognize or generate any other character or
character sequence as a line terminator. Limits MAY be imposed on line
lengths by servers (see section 4.5.3).

    In addition, the appearance of "bare" "CR" or "LF" characters in
text (i.e., either without the other) has a long history of causing
problems in mail implementations and applications that use the mail
system as a tool. SMTP client implementations MUST NOT transmit these
characters except when they are intended as line terminators and then
MUST, as indicated above, transmit them only as a <CRLF> sequence. 

RFC 2822 says

2.3 Body

    The body of a message is simply lines of US-ASCII characters. The
only two limitations on the body are as follows:

   - CR and LF MUST only occur together as CRLF; they MUST NOT appear
     independently in the body.

   - Lines of characters in the body MUST be limited to 998 characters,
     and SHOULD be limited to 78 characters, excluding the CRLF.

    Note: As was stated earlier, there are other standards documents,
specifically the MIME documents [RFC2045, RFC2046, RFC2048, RFC2049]
that extend this standard to allow for different sorts of message
bodies. Again, these mechanisms are beyond the scope of this document.

>The issue can be fixed if I make Savane convert all \r\n to \n before
>to send the notifications, but I am not sure this is very
>compliant. Anyway I do think this is a bug in Mailman. What do you
>think we (Mailman and Savane) should do?

I don't see any issues with mail delivered from Mailman having any
"doubling" of line terminators resulting in extra blank lines.

How does Savane inject its messages into the internet mail transport
system? If it is sending via SMTP, then it MUST send line terminators
as <CRLF> (or \r\n). If this results in doubling, then the receiving
SMTP server is non compliant. If it is sending messages via some non
SMTP intermediary, then it needs to format the messages as expected by
the intermediary.

Does Savane perhaps pipe outgoing messages directly to the Mailman
wrapper in the same way that an incoming MTA might do? If so, this is
_not_ an SMTP transfer and end of line sequences should be those of
the platform, i.e just \n for Unix.

Mark Sapiro <msapiro at value.net>       The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

More information about the Mailman-Developers mailing list