Mail filter install package 'lha' has no installation candidate

From the instructions at https://help.ubuntu.com/14.04/serverguide/mail-filtering.html#mail-filter-installation, one of the commands given fails:

[[
# apt-get install arj cabextract cpio lha nomarch pax rar unrar unzip zip
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package lha is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'lha' has no installation candidate
]]

Per instructions, I've checked the multiverse repository is enabled in /etc/apt/sources.list:

[[
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://gb.archive.ubuntu.com/ubuntu/ trusty multiverse
deb-src http://gb.archive.ubuntu.com/ubuntu/ trusty multiverse
deb http://gb.archive.ubuntu.com/ubuntu/ trusty-updates multiverse
deb-src http://gb.archive.ubuntu.com/ubuntu/ trusty-updates multiverse
]]

(If this is not what was meant, then the instructions here need improving.)

So far, I've been able to continue the installation by omitting 'lha' from the apt-get install command.