I was a bit surprised today to find the following on a Debian installation:
$ sudo apt-get install mdadm ... The following NEW packages will be installed: exim4-base exim4-config exim4-daemon-light guile-2.0-libs libfribidi0 libgc1c2 libgsasl7 libkyotocabinet16v5 libltdl7 liblzo2-2 libmailutils5 libmariadbclient18 libntlm0 libpython2.7 libpython2.7-minimal libpython2.7-stdlib mailutils mailutils-common mdadm mysql-common psmisc ... After this operation, 44.7 MB of additional disk space will be used.
There are a lot of dependencies here that don't seem to be related to managing a RAID array. I can see perhaps a very loose dependency to send an email when the RAID array fails, but beyond that, the above list doesn't make sense to me. It's 45 MB of dependencies.
What's the reason for these dependencies?