http://blogs.gnome.org/woody/2011/07/26/backup-your-gmail-in-a-few-easy-steps/

I’ll now move to explain a few details about my new configuration but before moving to tweak getmail’s main config file, please do the following change on  _retrieverbases.py* :

    return self._getmsgpartbyid(msgid, ‘(RFC822)’)

    to

    return self._getmsgpartbyid(msgid, ‘(BODY.PEEK[])’)

When done grab the following getmailrc and adapt it to your needs**:

    [retriever]
    type = SimpleIMAPSSLRetriever ## or SimplePOP3SSLRetriever.
    server = imap.gmail.com ## or pop.gmail.com for POP3.
    username = example@gmail.com
    password = password

    ## so-called Gmail’s labels should be listed one by one here  for getmail to retrieve mail from them successfully.

    mailboxes = (“INBOX”, “[Gmail]/Sent mail”,
    “ubuntu”, “gnome/example”, “linux/example”)

    [destination]
    type = Mboxrd
    path = ~/.getmail/backup.mbox

    [options]
    delivered_to = false ## No delivered_to header added automatically.
    received = false ## No received header added automatically.
    verbose = 2 ## getmail will print messages about each of its actions.

When done we should go ahead setting up getmail’s directories and config file:

    mkdir $HOME/.getmail

    cp $HOME/getmailrc $HOME/.getmail/

    ## Adapt $HOME/getmailrc to whatever dir you put that file into.

But…pretty much all the remaining work will be done by a small shell script I wrote:

    #!/bin/sh

    WORKDIR=$HOME/.getmail
    date=`date “+%d-%m-%Y_%H:%M”`

    if [ ! -f  $WORKDIR/backup.mbox ]
    then
    touch $WORKDIR/backup.mbox
    fi

    getmail > $WORKDIR/getmail.log
    OUT=$?
    if [ $OUT -eq 0 ]
    then
    mkdir -p $WORKDIR/backups/ && { mv $WORKDIR/backup.mbox $WORKDIR/backups/backup_$date.mbox ;}
    else [ $OUT -eq 1 ]
    exit 1
    fi

    ## Cleanup older than 3 days backups
    find $WORKDIR/backups/* -mtime +3 -exec rm {} ;
    cd $WORKDIR && { rm -rf oldmail-* ;}

This script will:

    Run getmail using the getmailrc config file you previously worked on.
    If the above command will be successful, it’ll create a backups dir into $HOME/.getmail and move the latest Mbox file there appending a date and time to its name. (by doing this we are sure next getmail run will happen on an empty backup.mbox file, thus it will just contain the latest content from your mailbox)
    It’ll re-create a backup.mbox file on $HOME/.getmail to avoid the next getmail run to fail.
    In the end, it’ll clean up older than 3 days backups to avoid a too crowded backups folder. (it removes the oldmail file as well since it is useless in our case)

In the end set up a cronjob that will run the above script and generate the backups for you every one hour:

    0 * * * * $HOME/.getmail/getmail_run.sh > /dev/null

Feel free to let me know if you’ve encountered any issue while following the above HowTo. Enjoy!

* /usr/share/getmail4/getmailcore/_retrieverbases.py on line 901.

** More documentation about the getmailrc file and syntax can be found on getmail’s documentation page.