Setting up a local imap server
To install a local imap daemon that will only listen to localhost connections, made via ssh tunneling. This is for use as a local backup of your imap files, or for keeping a remote backup somewhere.
This is not a mail delivery solution but rather a way to keep a backup of your email using to a MailDir directory that you can access using your email client. As each message is stored in its own file, you can also use normal tools like find|sed|awk|grep to find messages.
This setup can be installed locally or remotely on, for example, a raspberry pi. In that case you can enable a portforwarding rule in ~/.ssh/config to include something like LocalForward 127.0.0.1:2143 127.0.0.1:143
Install using aptitude install courier-imap courier-authdaemon
You can check the status using systemctl status courier-imap.service courier-authdaemon.service
Edit the file /etc/courier/imapd and modify the following settings:
Address to listen on, can be set to a single IP address.
< ADDRESS=0
> ADDRESS=127.0.0.1
Maximum number of IMAP servers started
< MAXDAEMONS=40
> MAXDAEMONS=80
Maximum number of connections to accept from the same IP address
< MAXPERIP=20
> MAXPERIP=40
The following setting is optional, and causes messages from the given folder to be automatically deleted after the given number of days.
< IMAP_EMPTYTRASH=Trash:7
> #IMAP_EMPTYTRASH=Trash:7
Change the directory name of the maildir directory.
< MAILDIRPATH=Maildir
> MAILDIRPATH=/home/pi/MailDir
Then restart the service using systemctl restart courier-imap.service courier-authdaemon.service.
When I did this I got a strange error about but installing the package gamin fixed it. Which is a Library providing the FAM File Alteration Monitor API.
Filesystem notification initialization error -- contact your mail
administrator (check for configuration errors with the FAM/Gamin library)