bug#13413: 24.2.92; Didn't find `rmail-summary-line-count-flag'

[Eli Zaretskii]

> Date: Fri, 11 Jan 2013 21:56:53 +0800
> From: Xue Fuqiao <xfq.free@gmail.com>
> 
> In (info "(emacs) Rmail Make Summary"):
> 
> The variable `rmail-summary-line-count-flag' controls whether the
> summary line for a message should include the line count of the message.
> 
> I couldn't find this variable after I required the `rmail' package.

You need to require rmailsum.  (The "rmail-summary" part hints at
that.)  Rmail is not all defined on a single rmail.el file, there are
a few more.

Closing.