[Mailman-Developers] Regexp filtering

[Stephen J. Turnbull]

Adam McGreggor writes:

 > Or could we meet user expectations (real users, not geeks), [and
 > allow glob syntax].

Definitely worth discussing, but my initial reaction is negative for
the reasons discussed below.

 > Simples:
 >     *@mail.ru
 >     *@*mail.ru
 >     ?????@mail.ru

Are those anchored?  At the beginning of string?  At end?  Is there
really a use case for "?"?  I don't see this as an obvious feature.
Globs are also too blunt for the use case, especially since bad actors
do deliberately use fine distinctions between well-known domains and
their own sinkholes of depravity when phishing.  Users are likely to
be lazy, using "*@*mail.ru" to catch both "badactor at mail.ru" and
"badactor at spamsource.mail.ru", trashing "niceguy at goodmail.ru"'s posts
in the process.

 > Off the top of my head, the syntax would define if it's an absolute
 > address (foo at example.com) vs a regexp.

"foo at example.com" is unambiguous, but "foo+mailman at example.com" is
not.  That's a big trap for users, who surely know exactly what they
mean by that (and it's not foooooooooooomailman at example.com!)

In theory we could use globs as well (some of the modern VCSes permit
glob or regexp syntax), but it's not a serious data loss issue for a
VCS if a mistake is made.  You just run the add command again with -f,
or uncommit, or whatever.  Granted, a perverse enough user could fail
to add a file, commit, then overwrite the file, but this is much less
serious than the possibility that a particular user would end up as
collateral damage to a spam filter.

Steve