Bug 135420

Here's an excerpt (yeah, but/pasted) from the headers of a recent gnats acknowledgement of a submitted PR:

| From: FreeBSD-gnats-submit@FreeBSD.org
| Subject: Re: docs/133855: New mailing list, freebsd-gecko
| Reply-To: FreeBSD-gnats-submit@FreeBSD.org, freebsd-doc@FreeBSD.org
| In-Reply-To: Your message of Sun, 19 Apr 2009 07:10:26 -0700 (PDT)
|         <200904191410.n3JEAQi4026966@albert.catwhisker.org>
| Status: RO
| Content-Length: 434
| Lines: 14

Note the content of the In-Reply-To header: that is syntactically incorrect, as RFC 2822, section 3.6.4 contains:

| 3.6.4. Identification fields
| 
|    Though optional, every message SHOULD have a "Message-ID:" field.
|    Furthermore, reply messages SHOULD have "In-Reply-To:" and
|    "References:" fields as appropriate, as described below.
| 
|    The "Message-ID:" field contains a single unique message identifier.
|    The "References:" and "In-Reply-To:" field each contain one or more
|    unique message identifiers, optionally separated by CFWS.
| 
|    The message identifier (msg-id) is similar in syntax to an angle-addr
|    construct without the internal CFWS.
| 
| message-id      =       "Message-ID:" msg-id CRLF
| 
| in-reply-to     =       "In-Reply-To:" 1*msg-id CRLF
| 
| references      =       "References:" 1*msg-id CRLF
| 
| msg-id          =       [CFWS] "<" id-left "@" id-right ">" [CFWS]
| ...

Note that there is no defined syntax for commentary in the In-Reply-To header.

[I cannot claim credit for noticing this first.  A correspondent informed me of it, in my capacity as postmaster@freebsd.org.]

How-To-Repeat: File a PR at FreeBSd.org, then examine the headers of the acknowledgement email message.