[Evolution-hackers] IMAP Features plugin -- still useful?

[Matthew Barnes <mbarnes redhat com>]

The IMAP Features (imap-headers) plugin allows you to specify which
headers to download from an IMAP server when building folder summaries.
This is useful for instance when you have client-side filters that
operate on particular headers not normally included in an envelope.  It
appears in the account editor as a tab labeled "IMAP Headers".

But the plugin only applies to accounts using the older IMAP provider.
Does this feature also make sense to support in the IMAPX provider, or
should it die out with the older IMAP provider?