NAME

mail2dt - Docker Image for E-Mail Archiving

VERSION

Version 0.0.1

This program was first announced here.

LICENCE AND COPYRIGHT

Copyright (c) 2020 Matthias Nott (mnott (at) mnsoft.org).

Licensed under WTFPL.

Credits

This work is based on the minimalistic dovecot container created by Alan Dixon.

INTRODUCTION

        This docker image creates a local IMAP server based on
        dovecot that you can use to transfer mails.

        For example, you can transfer mails between Outlook and
        Apple Mail, or you can use it to transfer Mail between
        those and DevonThink.

SYNOPSIS

In all clarity, if you are happy with the following process that you have to use if you do not use this program, you can skip this whole program and go on with your life:

1. Click on the import icon on the left top of DevonThink
2. Right-Click on the list of email programs that DevonThink sees, and choose refresh
3. Click on the folder or folders that you want to import from
4. Click on one of those mails that are shown after a while, and press Cmd+A to select them all
5. Make sure you have chosen the right import target location, e.g. your Inbox, and click on Import
6. Switch over to your Mail client and delete those Mails there
7. Empty the Trash for your Email client.

As you can imagine, that process is rather quite annoying if you want to not end up having a long email backlog of mails that are not yet in DevonThink. It is tedious, repetitive, and hence there should be a better way.

To choose from only one source location in my email client (Outlook in my case), I had already created a rule that would move just any mail or mails that I had selected, into some folder - thereby, I would have to import those Mails only from that folder. But that does not otherwise reduce the number of steps to do really.

So this program, or collection of scripts rather, chooses another way: It uses the idea of creating a local mail server, a so-called IMAP server that runs on your computer, as an intermediary. And since that server actually stores all Mails on the file system of your computer, in a file format that DevonThink can immediately understand, the basic task now is to use move the mails not into a folder of your mail client, but actually into a folder of that new mail server - to then move the files from there into DevonThink's Inbox.

There will hence be no distinct import process for DevonThink that you need to manually start. To the contrary, you can just move the files into the IMAP server right out of the Mail program - using an email rule similar to what I spoke about before - and then within DevonThink, just hit one button to have them not only imported, but also filed away if you want.

Sounds good, but also probably rather complicated. So to facilitate all of this, I've wrapped the most complicated bit of it, the "running an email server on your laptop" into a so-called Docker container. What that really means is that you do not need to configure anything (unless you want to, and I am going to give details on those options further below). You rather

1. Download and Install Docker
2. Download ("clone") this Git repository
3. Start the Docker Container
4. Configure your Mail Client to see the email server running inside the Docker Container
5. Copy one Script over to DevonThink's Script Directory
6. Restart DevonThink, and add the script to it's toolbar

Then in the future, you just do these simple steps to file away your Mails:

1. In your Mail application, Move the Mails to that email Server's Inbox
2. In DevonThink, click that new button on the toolbar

Other Uses

Note that since this particular process is meant to facilitate the co-operation between your Mail client and DevonThink, and DevonThink is a Mac application, of course the whole process is very Mac specific. But as a bonus, the Docker container containing the IMAP server is not at all Mac specific - it would run just fine on another Operating system, and you could use it to, e.g., transfer Mails between two different kinds of Mail clients: For example, people tend to struggle with getting their Mails out of Outlook and into some other program. Using the intermediary IMAP server that comes within this Docker container makes this a very simple thing: You just configure the source and target Mail clients to connect to that server.

INSTALLATION

Prerequisites

Docker and Docker-Compose

Head over to Docker, if you have not already done so. Install Docker on your machine, and run it. Docker is a program that can run other stuff in an isolated form, similar to a virtual machine, but without all the overhead that such a virtual machine would typically consume.

• Note: If you would run Docker on Unix, you should use your distribution's preferred way to install Docker, and you would also install docker-compose. That one comes bundled with the Docker version for Mac, but e.g. on Ubuntu, it is a separate download.
• Note: On Windows, you would download Docker from here.
• Note: On Unix or Windows based machines, before installing Docker, make sure that you have switched on Virtualization in your BIOS (the feature is often under either Configuration or Security, and is often called Intel Virtualization Technology and VT-d Feature: Enable both). If you fail to do this, the image may not start up.

Git

If you don't want to use Git

If you do not want to use Git regularly, you can just download this whole repository into it's own directory. So for that, you would click here, download that zip file, extract it to your home folder so that you essentially get a folder

~/mail2dt

Then, head over to the configuration part below.

If you want to use Git

Of course, using Git has some advantages; for instance, you can more easily keep track of changes to the program. Also it just makes you look so much more competent. So of course, just install Git.

• Note: If you are working on a Windows system, make sure to configure Git, when it installs, to not automatically convert Line Ends ("CR/LF"). Shouly you have configured it wrongly, you can do this on the command line:

    git config --global core.autocrlf false
  

Finally, you open a command line and do this:

cd ~
git clone https://github.com/mnott/mail2dt
cd mail2dt

Summary of the Prerequisites

1. You should have installed and started Docker
2. You should have created a directory mail2dt beneath your home directory (either by just downloading and extracting the ZIP file of this repository, or by installing Git, and cloning this repository - into your home folder).

CONFIGURATION

We are going to show you the least amount of steps that you can take to configure for you. This entails the following steps:

1. Start the Docker Container (that's where the IMAP Server is running)
2. Configure your existing Mail Client (so, Apple Mail or Outlook)
3. Add the import script to DevonThink's toolbar, and optionally configure that script if you also want it to immediately file away the newly imported emails.

Start the Docker Container

Since above you already went into the ~/mail2dt directory, within that directory, you can simply say

./run.sh

That will install and run the docker image like so:

mnott[17:10:23]@MatthiasMacBook:~/mail2dt$ ./run.sh
uid=90(dovecot) gid=101(dovecot) groups=101(dovecot),101(dovecot)
Jun 12 16:21:30 6a399b7c3af8 syslog.info syslogd started: BusyBox v1.27.2
Jun 12 16:21:30 6a399b7c3af8 mail.info dovecot: master: Dovecot v2.2.36.4 (baf9232c1) starting up for imap (core dumps disabled)
Jun 12 16:21:30 6a399b7c3af8 mail.info dovecot: ssl-params: Generating SSL parameters
Jun 12 16:21:30 6a399b7c3af8 mail.info dovecot: ssl-params: SSL parameters regeneration completed

You might see a lot more stuff since it'll install at the first start.

To stop the container, you just hit Ctrl+C. See below on how you can run that container in the background, without keeping your command line open. For now, keep it running and configure your Mail Client...

Configure the Mail Client

If you have just cloned the git repository and do not want to bother about any configuration, once you have started the docker container (more on that below: You need to start the docker container first, before you configure your mail client), all that you do is to go over to your mail client, tell it that you want to connect to a new mailserver. As mailserver, you use:

Incoming Mail Server: 127.0.0.1
User name: mailuser
Password: mailpass

For the moment, we assume that we are going to move mails into the Inbox of that new mail server. Further below, I'll explain what you need to do if you want to have the mails going through some other folder on that new Mail server. So go ahead, and copy some Mail into that new mail server's Inbox.

Configure Devon Think

The rest of this section shows how to modify where this program is going to run, and how to change the username and password. But before we do so, we also want to utilize a nifty little script that I wrote for integration with DevonThink.

You can move the file

~/mail2dt/devonthink/ArchiveMails.scpt

into the directory

~/Library/Application Scripts/com.devon-technologies.think3/Toolbar

If you move the file into the above-mentioned directory, and restart DevonThink, you can then right-click on the toolbar and chose Customize Toolbar.... You should see that script's name, so probably ArchiveMails, towards the bottom of the screen, just left of the Search field. From there, you can drag the script's icon anywhere on your toolbar.

But before you click on that new button, please wait to understand the script itself. You can edit the file with Apple's ScriptEditor app, by just double-clicking on the file.

Right at the top of the file, you'll see this:

-- set ruleList to {"00 - Import Emails", "Rule 1", "Rule 2", "Rule 3"}
set ruleList to {}

Actually, this script can do a lot more than just importing Mails. For that, it would be sufficient to copy the mails into the Inbox of DevonThink. And yes, the script does just that by utilizing a script that comes with it (see the line do shell script ... further down in the script).

But I thought, let's take it a bit further. At the top, you see, commented out using -- at the start of the line, a way how you can reference a sequence of mail rules to be applied directly to the mails. The second line defines just an empty list, so that nothing is really done except for copying the mails into the Inbox.

Yet if you want to automate further, you can create any number of rules that you want to have working on your mails, and invoke them right after importing the mails.

For example, the first rule that I have is 00 - Import Emails. That rule is a smart rule that takes all items within the global Inbox of DevonThink of where the file name ends with .eml and moves those items to another folder (since I have multiple databases, I am using the Inbox of my current email database). So that way, I am separating out of my global Inbox all mails from non-mails. The reason to do so is that for some reason, a DevonThink database's inbox does not have a representation within a directory, except for the global inbox.

Next I have a bunch of other rules that file the mails further into other folders. So for example, I might say, search in

• and I'd use now the location where the mails were put by the 00 - Import Emails rule - and move mails with a certain sender to their own folder.

That ruleList is worked through sequentially. The last rule that I have, and that is of immense use for me, is a rule Not to Me: There I search for all Mails that do not have me on the From: or To: headers (and that are not form a list of VIPs), and move them over to a folder Not to Me.

So once you've set all this up - and you don't really need to do anything if you are happy with first seeing the Mails arrive in your Inbox - then you are done.

Use

In daily use, you just would make sure that the Docker container is running. If it is not, for most email clients that I have tried (Apple Mail, Outlook), that is not really a problem: If you try, from within them, to move a mail into the new mail server, they will just wait for that server to come online again, and only then will the mails arrive there. And until they are there, you can try the import script within DevonThink as much as you want, it just will not find any new emails to import.

So when you have your Docker container running (see below for a way to run it in the background), then you just copy or move the mails into the new mail server's inbox, and in DevonThink, you click the new ArchiveMail button. There is a 15 second wait withini that script, and if the mails don't arrive at the first try, it may just be that your mail client is a bit lazy when copying the mails over.

Futher Configuration Options

These options here are really just meant as a more detailed documentation on how everything hangs together. If you are happy with using the default configuration used above, you can skip this.

Directories

The Application's Directory

There is not a whole lot to configure. The directory mail2dt is referenced in a small number of places:

• docker-compose.yaml
• devonthink/mail2devonthink.sh
• devonthink/ArchiveMails.scpt

docker-compose.yaml

docker-compose.yaml is the configuration file of the docker image. It needs to refer to an actual directory. What we are doing there is to share, with the docker image, two directories on the computer where docker is running. These directories are, from the point of view of mail2dt,

• ./config: Contains the configuration for the IMAP server
• ./mail: Will contain the actual emails

And that is really what is behind the whole idea here: If you copy a mail into this IMAP server, what happens is that it will create a file of that mail (containing all attachments) on disk. And the location where we want him to store that file is not within the container, but within a location outside of that container, so that with the script described below, we can move that file from there into the inbox of DevonThink.

devonthink/mail2devonthink.sh

This is the script that copies the files from where the IMAP server within the Docker container has put the email files, into the inbox of DevonThink.

At the top of that file, you can see

ROOTDIR=~/mail2dt

You would need to change that directory to something else if you had installed the git repository somewhere else.

devonthink/ArchiveMails.scpt

That file you should open with Apple's Script Editor application (it is a binary file format). It contains a direct reference to the directory mail2dt:

do shell script "~/mail2dt/devonthink/mail2devonthink.sh"

That is so because if otherwise run from within DevonThink, the file would not find the shell script. Adapt this file if you want it to pick up the mail2devonthink.sh from another location.

The IMAP Server

If you want to keep the default user, mailuser, and its password, mailpass, you do not need to change anything. That should be fine, as after all, you are running this server only locally, and only as a temporary vehicle to transfer mails.

If you want to change these settings, you need to head over to the config directory. Within dovecot.passwd, you can replace the string mailuser by a mail user name that you might like (it appears twice in that file). If you do so, you also need to replace that same username into the file devonthink/mail2devonthink.sh: At the top, there is a setting

MAILUSR=mailuser

You would have to change that settings.

Similarly, within dovecot.passwd, you could exchange the string mailpass with something else. Of course, if you do change mailuser or mailpass, you need to configure your mail client accordingly.

Also, within the config directory, there are two key files and a generator, make_keys.sh for those. These files are required for the IMAP server to use SSL, and they are likewise not really relevant content-wise. The make_keys.sh uses openssl to generate those files. You can use that file as a reference and generate your own files, if you want. the IMAP server just knows about the file names, and expects them to be in that place.

The Mail Transporter

Within the devonthink directory, there is a file mail2devonthink.sh. That file is there to take the files from the IMAP server and move them over to the inbox of DevonThink.

The script tries to be a bit clever with regards to naming the files within the inbox of DevonThink: The IMAP server names the files arbitrarily, and if we would just copy those files, with their original names, into DevonThink, the names shown would not be readable. Hence what we do here is to use a second script, root/usr/local/bin/subject-decoder.pl, to read each mail's subject line, and create a filename out of that (since this file requires some Perl modules, we run it inside the Docker container where we can ensure we have what we need). And in case the subject would not be unique, to not overwrite a potentially existing file in the inbox of DevonThink, we append a counter to the filename if necessary.

If you look at the header of that file, you'll see some configuration options:

ROOTDIR=~/mail2dt
MAILUSR=mailuser
DTINBOX=~/Library/Application\ Support/DEVONthink\ 3/Inbox/
MAILDIR=$ROOTDIR/mail/$MAILUSR/Maildir
CLEANUP=false
VERBOSE=true

The ROOTDIR and MAILUSR we already spoke about. The DTINBOX variable contains the actual location of your DevonThink inbox. If you have that in another place, change that reference here.

The MAILDIR refers to the source directory for the emails; in other words, to the directory where the IMAP server would store its mails, and from where the mail2devonthink.sh would take them to transfer them over to the DevonThink inbox.

Since there is a full fledged IMAP server that is running within the Docker container, you might want to use some subdirectory of that MAILDIR (in other words, a folder within your IMAP server). If you do so, just create that folder from within your Mail client, copy some email there, and observe what's going on within that MAILDIR folder. What you are looking for is the parent directory of the actual directory where that mail is going to show up (it is going to have some funny file name). The mail will end up inside some new or cur directory beneath the directory which you want to set as value to the MAILDIR variable.

If this is all gibberish to you, then just don't bother changing any of those settings above...

There is one more thing in that file that you should consider, whether you understood the previous parts or not. There is that CLEANUP variable at the top. It is set to false by default. If you want to remove the mails from the IMAP server (so that you don't have to delete them within your Mail client after transferring them to DevonThink), then you can set this to true. Make sure you have really tested everything well before you do that. You can always run the script just from the command line like so:

./devonthink/mail2devonthink.sh

and if you do so, you will then see what is going on. If you want to make the script rather not say what it does, you can later set the VERBOSE variable to false.

The Docker Container

Far above, you've learned to use the

./run.sh

script to start the Docker container. It will optionally download what is needed, create the container, and run it. To get out of it, you just hit Ctrl+C.

From a directory structure perspective, there are three directories that are relevant here.

• The config directory is there to configure the password of the IMAP server.
• The mail directory is where the mail files are put by the IMAP server.
• The root directory contains the actual installation of the IMAP server.

The root directory is configured within the Dockerfile, and the config and mail directories are configured within the docker-compose.yaml.

The run.sh starts the Docker container in an interactive mode, but why not make this even a bit nicer. I'm also embedding, as part of this repository, a Docker control script that I've written. It's just called d. You can call it like so:

./d

It will come up with a menu for you:

-------------------------------------------
       D O C K E R      C O N T R O L
-------------------------------------------

Compose

[up]    Up
[down]  Down

Containers

[la]    List    All       Containers
[ls]    List    Running   Containers

[start] Start   Container
[stop]  Stop    Container
[rm]    Remove  Container
[rms]   Remove  Stopped Containers

Images

[lsi]   List    All       Images
[lsd]   List    Dangling  Images
[rmd]   Remove  Dangling  Images
[rmi]   Remove  Image

[edit]  Edit    Dockerfile
[build] Build   Image

Console

[con]   Connect to Container

Enter choice or q to exit:

So if you want to take that docker container up, you can just type up followed by Enter. To take it down, you can just say down, followed by Enter.

ls will list the running containers:

Enter choice or q to exit: ls

Running Containers:

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS                  NAMES
8fa24fa71098        mnott/mail          "/run.sh"           34 seconds ago      Up 33 seconds       0.0.0.0:993->993/tcp   	mail2dt_mail_1
Press [Enter] key to continue...

which you can then also stop like so:

Enter choice or q to exit: stop

Running Containers:

CONTAINER ID        IMAGE               COMMAND             CREATED              STATUS              PORTS                  NAMES
8fa24fa71098        mnott/mail          "/run.sh"           About a minute ago   Up About a minute   0.0.0.0:993->993/tcp   mail2dt_mail_1
Enter Container name to stop: [] 8f

8f

Press [Enter] key to continue...

Notice how I have used a part of the CONTAINER ID to identify which container I wanted, in this case, stop. You can also even connect to the command line within the runnign Container using the con command:

Enter choice or q to exit: con

Running Containers:

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS                  NAMES
8fa24fa71098        mnott/mail          "/run.sh"           3 minutes ago       Up 29 seconds       0.0.0.0:993->993/tcp   mail2dt_mail_1
Enter Container name to connect to: [8f]

bash-4.4# ls
bin     config  dev     etc     home    lib     mail    media   mnt     proc    root    run     run.sh  sbin    srv     sys     tmp     usr     var
bash-4.4# exit
exit

Press [Enter] key to continue...

And finally if you want to delete the container, and the "image" that it was built out of, you can do first remove the container, and then its image, with the corresponding menu options.

So this part is really just a very useful addon that you can use for any Docker containers. Especially the management of containers and images has been very useful for me, as I am too lazy to try to remember all the command line options that Docker comes along with.