看来我无法mailutils在 Ubuntu 18.04 中安装。这是一个依赖性错误，我在其他地方也找不到有关此问题的信息。
命令： sudo apt install mailutils
输出：
The following packages have unmet dependencies:
mailutils : Depends: guile-2.0-libs but it is not going to be installed
Depends: libmailutils5 but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
然后我运行了这个：
sudo apt install guile-2.0-libs
输出：
The following packages have unmet dependencies:
guile-2.0-libs : Depends: libgc1c2 (>= 1:7.2d) but it is not installable
Depends: libltdl7 (>= 2.4.6) but it is not installable
E: Unable to correct problems, you have held broken packages.
我尝试libgc1c2手动安装：
sudo apt install libgc1c2
输出：
Reading state information... Done
Package libgc1c2 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 'libgc1c2' has no installation candidate
答案1
缺失的依赖 guile-2.0-libs可从main存储库获取。mailutils及其依赖性libmailutils5可从 获得universe，编辑您的内容/etc/apt/sources.list如下：
deb http://us.archive.ubuntu.com/ubuntu/ bionic main restricted universe multiverse
deb http://us.archive.ubuntu.com/ubuntu/ bionic-security main restricted universe multiverse
deb http://us.archive.ubuntu.com/ubuntu/ bionic-updates main restricted universe multiverse
deb http://us.archive.ubuntu.com/ubuntu/ bionic-proposed main restricted universe multiverse
然后运行：
sudo apt update
sudo apt install mailutils