[Bug 302362] [NEW] Too eager spam filtering with limited evidence

[era]

Public bug reported:

Binary package hint: thunderbird

When you first take the junk email filter into use, it is much too eager
to classify messages as spam.  If you also check the "automatically move
to junk folder" or a related option, you are unlikely to notice all the
false positives.

I have not yet tried these repro steps, but I think they should work.

1. Be the owner of an mailbox which receives a fair amount of spam.
2. Create a new account for this mailbox (same settings as an existing account is fine, I believe).
3. Open the mailbox and click the junk email symbol on a few spam messages.
4. Exit Thunderbird.
5. Wait for some mail to arrive.
6. Reopen Thunderbird and visit the account again.  Run junk email controls.

Expected outcome:

Because there is only very scant evidence to draw from, it should not
yet mark any messages as spam.

This is how e.g. SpamAssassin works; it refuses to use the Bayesian
feature until it is adequately trained (where "adequately" is simply
defined as having learned from a fixed minimum number of both spam and
ham samples; the default threshold is 200 each).

Actual outcome:

Lots of false positives.

vnix$ lsb_release -rd
Description:    Ubuntu 8.10
Release:        8.10

vnix$ apt-cache policy thunderbird
thunderbird:
  Installed: 2.0.0.18+nobinonly-0ubuntu0.8.10.1
  Candidate: 2.0.0.18+nobinonly-0ubuntu0.8.10.1
  Version table:
 *** 2.0.0.18+nobinonly-0ubuntu0.8.10.1 0
        500 http://security.ubuntu.com intrepid-security/main Packages
        100 /var/lib/dpkg/status
     2.0.0.17+nobinonly-0ubuntu1 0
        500 http://fi.archive.ubuntu.com intrepid/main Packages

** Affects: thunderbird (Ubuntu)
     Importance: Undecided
         Status: New

-- 
Too eager spam filtering with limited evidence
https://bugs.launchpad.net/bugs/302362
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