Custom Mailfilter for Uberspace 7

Attention: This mailfilter is intended to work for Uberspace 7 – a setup for Uberspace 6 with DSPAM and SpamAssassin can be found here.

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This script can be used for setting up a customized mailfilter config with Rspamd and Bogofilter on an Uberspace 7 server. Every message will be filtered by these two services: Learning false positives or false negatives is realized with Bogofilter, while Rspamd uses multiple filtering and statistical methods to generate a spam score (which is later used for filtering). Custom rules can be added too. If messages are not correctly recognized as ham, they can be manually taught as ham by setting up a whitelist (one email address each line).

At this time Rspamd isn't configurable for learning on userlevel (see manual for the actual default behavior). According to Uberspace this might change in the future...

The main goal of this filter is a more intuitive workflow with less special folders (like Learn as Spam and Learn as Ham) when showing messages to Bogofilter via a customized spam-learn script so it can learn. This is realized by marking messages, recognized or reclassified as spam, with the header X-Spam-Folder: YES, which is removed for messages that are reclassified as ham. All reclassified messages will be re-delivered via maildrop. Finally, teaching spam or ham works like this:

• When moving a message from 'Junk | Spam | Junk-E-Mail' to 'Inbox' it will be learned by Bogofilter as Ham
• When moving a message from 'Inbox' to 'Junk | Spam | Junk-E-Mail' it will be learned by Bogofilter as Spam

Please Note: Only messages of the last 24 hours are interpreted by spam-learn to prevent slow scanning due to big folders.

Installation of Bogofilter

Get Bogofilter and install it like this:

  wget -O bogofilter.tar.xz https://sourceforge.net/projects/bogofilter/files/bogofilter-stable/bogofilter-1.2.5.tar.xz/download
  tar -xvf bogofilter.tar.xz
  cd bogofilter-1.2.5
  ./configure --with-database=sqlite3 --prefix=$HOME
  make
  make install

(Please adapt to current bogofilter version in the future)

Installation of Mailfilter

Core Files

• Set up .qmail and maildrop before (see .qmail and maildrop documentation for setting up)
• Rename .mailfilter to .mailfilter-EXT (replace EXT by your namespace) before.
• Put the file .mailfilter (or .mailfilter-EXT) and the folder .mailfilters in the home directory of your uberspace.
• Remember to set the correct file permissions: chmod 600 ~/.mailfilter (or .mailfilter-EXT)
• mailfilter(-EXT) logfiles can be found in ~/logs
• spam-learn goes to ~/bin (its database will later be found in ~/.bogofilter)

Adding spam-learn as a cronjob

Add spam-learn as a cronjob that is running once per hour:

Call crontab

  crontab -e

and add this lines

  # Call spam-learn hourly
  @hourly ~/bin/spam-learn

Credits and used code (snippets)

• Custom Filter for Uberspace 6 with DSPAM and SpamAssassin
• Uberspace 7 manual for filtering mails

Feedback

This is work in progress, so do not hesitate to give feedback and/or provide pull requests.