When I click the paper clip icon to add an attachment, I would like to be able to select emails from my Inbox or another account folder. Currently, I can only attach specific file types (images, videos, audio, etc.) or from specific folders (downloads, internal storage, SD card) or apps (Gallery, Google Drive, some installed file explorers, etc.).
Alternatively, I would like to be able to select multiple emails to be forwarded as attachments in the same new email. Currently, I can only long-press a single email to get the Forward as Attachment option.