A Mutt Journey: Filter mails with imapfilter

About a month ago, I decided to switch to Mutt to read my emails. I kept my GMail account, but I don't use the web interface anymore. It took me a long time to prepare a complete enviromnent.

Currently, i'm using:

• imapfilter to filter mails

• offlineimap to download my mails

• notmuch to quickly search all my mails

And of course Mutt. To be precise, I use mutt-kz, a fork of mutt with very good notmuch integration.

I'll try to explain each part of my environment in a series of articles on this blog. The first one will be about imapfilter.

imapfilter is a mail filtering utility. It connects to a remote server using IMAP and is then able to move, copy or delete mails around. You can use it for several tasks:

• Delete unwanted mail

• Move mails into folders according to rules

What is pretty cool is that the configuration is entirely made in Lua. It is quite easy to write rules and then apply them to several mailboxes as if you were programming.

Another advantage of imapfilter is that it works at the server level. Therefore, even if you use your web client from time to time or check your mail on your phone, the changes will still be viewable.

The configuration is done in the ~/.imapfilter/config.lua file. The configuration is quite easy, you have to declare an IMAP object as the account.

local account = IMAP {
    server = 'imap_sever',
    username = 'username',
    password = 'password',
    ssl = 'ssl3',
}

As the configuration is in Lua, you can easily get the password from another file. For instance, here is my account declaration:

local account = IMAP {
    server = 'imap.gmail.com',
    username = '[email protected]',
    password = get_imap_password(".password.offlineimaprc"),
    ssl = 'ssl3',
}

-- Utility function to get IMAP password from file
function get_imap_password(file)
    local home = os.getenv("HOME")
    local file = home .. "/" .. file
    local str = io.open(file):read()
    return str;
end

It gets the password by reading a file in the home directory.

Once, you have the account, you can check the status of a folder with the check_status() function. For instance:

account.INBOX:check_status()
account['[Gmail]/Trash']:check_status()

You can run imapfilter simply by launching imapfilter on the command line. Once imapfilter is run, it will print the status of the folder you choses:

38 messages, 0 recent, 6 unseen, in [email protected]@imap.gmail.com/INBOX.
70 messages, 0 recent, 67 unseen, in [email protected]@imap.gmail.com/[Gmail]/Trash.

Several functions are important:

• select_all() on a folder allows you to get messages from an account to them perform action on them

• contain_subject('subject') on a list of mails allows you to keep only the mails that contains 'subject' in their subject

• contain_from('from') on a list of mails allows you to keep only the mails that comes from 'from'

• contain_to('to') on a list of mails allows you to keep only the mails that are addressed to 'to'

• delete_messages() on a collection of mails deletes all of them

• move_messages(folder) on a collection of mails moves all of them to another folder.

You can also mix different IMAP accounts, you don't have to use only one.

For instance, if you would delete all the mail coming from me, you could do:

mails = account.INBOX:select_all()
filtered = mails:contains_from("[email protected]")
filtered:delete_messages()

Or you could move all the mails containing Urgent in the subject line to an IMAP folder:

mails = account.INBOX:select_all()
filtered = mails:contains_subject("Urgent")
filtered:move_messages(account["urgent_mails"])

If you want some more examples, you can take a look at my imapfilter configuration.

The best way to start using it is to look at examples, there are plenty of them in the internet, especially in Github dotfiles repositories.

The reference documentation is available using 'man imapfilter_config', there is plenty more to see.

For more information, you can also consult the offical site.

That is it for this part of the mutt series. In the next post about mutt, I'll talk about how I use offlineimap to get my mails.

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