How do I delete a single email from a vendor thread in the Promotions category?

See also the response to

Deleting one email from a thread - Apple Community

Now that iPhone Mail Categories have been rolled out it would be helpful to understand why deleting (aka send to trash) is an “all or nothing” exercise.

Surely it is easy to understand that only a selection of emails from, say, a vendor need to be deleted as part of the daily pruning of your email inbox.

Other email threads with that same vendor need to be preserved for future reference. The trouble is all email from the one vendor is now presented as one digested thread and yet you and I both know that this not how those emails are natively grouped by the email protocol. This new grouping is an App-level grouping.

There is only a “delete all” option.

There needs to be a “delete selected” option as well.

WORKAROUND:

There are two work arounds that I can imagine:

1. Switch back to Lists view. (Meh … I like fresh challenges !)
2. Manually categorize select vendors so that they appear in the Primary category.

Email arriving in the Primary category is only presented as a thread when the correspondence shares the same Subject line. I.e these are classic email “threads”

We need a thread-like synonym for the grouping of all email from one email address in one of these new Mail Categories.

[Re-Titled by Moderator]