BT email rules not working

So, I just spent the evening rejigging my parents' email rules with BT. They seemed to stop working sometime in January 2021, and I've just worked out why.

BT have changed how comparisons like is and ends with work on the From: field (and possibly others). Previously, the email address was extracted from the field, so it didn't matter whether the whole text of the field read any of these ways:

From: j.bloggs@example.com
From: Joe Bloggs <j.bloggs@example.com>
From: "Joe Bloggs" j.bloggs@example.com

Can't be certain that I've remembered that third form correctly; it's in an RFC somewhere anyway. However, I don't think I've seen it for a long time, so I've going to assume it's fallen out of favour, and focus on the other two.

Under the new mechanism, From: is j.bloggs@example.com will only match the first form. You'll now also need a From: contains <j.bloggs@example.com> to guarantee a match. You can't use multiple operators like is and contains on the same field in the same rule, so you must duplicate the rule, and maintain it. You could, of course, match both j.bloggs@example.com and <j.bloggs@example.com> in the same rule with contains, and you'll probably get away with it, but you'll be left scratching your head when bob.j.bloggs@example.computing.invalid ends up in the same place. Also, if they change it back without notice, your is rule will continue to work.

From: ends with @example.com will also fail to match the second form. You need From: ends with @example.com> too now. Fortunately, you can do that with an extra entry in the same rule; you don't need a duplicate rule. However, bear in mind that you can only have 15 From: entries in a single rule.

To: and CC: can have multiple addresses. Some experimentation is required to determine whether they are automatically split and tested separately.

While I'm in gripe mode, BT rules could do with a few other features:

• Match on List-Id: to pick out mailing-list posts unambiguously.
• Filter out those damn subject-line tags like [zarquon users] that needn't pollute mailing lists when they've already been sorted into the right folder.
• Mark messages as read.