Taking control of your own technology

Manually Fulfilling Dependencies on Debian


msmtp is yet another Mail Transfer Agent that merely relays the outgoing email message to another (e.g. your ISP’s) SMTP server. There seems to be quite a lot of these, but this one seems to be the most actively maintained - see its homepage on sourceforge for more information and documentation. At time of writing, the last stable release is March 9, 2014 which is very recent.

Other similar ones, such as ssmtp, esmtp and nbsmtp, still seem to work, they are pretty simple programs with few dependencies apart from the C environment which basically never changes anymore and they are recompiled and repackaged regularly by the distributions.

I have a machine running on Debian stable but wanted a newer version of msmtp than is packaged for stable. So I cloned the source code using git and compiled it.

However, after removing the default mail transfer agent (Exim), Debian’s apt command is desperate to re-install it.

So I needed to tell the system that I already have a mail transfer agent. This post explains how I did it. I don’t know if this is the correct ‘modern’ way to do it, but it worked for me, and it is quite interesting because it exposes a little of how Apt works under the hood.

Fortunately, my problem is the use case given in the old Apt Howto under the section called 4.1 How to install locally compiled packages: equivs there is more useful information there.

The package that helps us to circumvent Debian package dependencies is called equivs, so first I needed to install that. sudo apt-get install equivs

sudo apt-get install equivs

Next I ran the following command.

equivs-control msmtp-git

This created a template Debian control file. I gave it a meaningful name, i.e. msmtp installed from git.

I added the following lines:

Package: msmtp-git
Provides: mail-transport-agent

The Provides line is the key, it tells the system that a mail-transport-agent is installed.

Then I created a .deb from this control file.

equivs-build msmtp-git

Lastly I installed the deb:

sudo dpkg --install  msmtp-git_1.0_all.deb

Pretty weird but it works.