mail_attach_existing_attachment

Purpose

Allow users to include attachments already linked to a record when sending emails via the mail compose wizard.

Features

mail.compose.message: Adds an object attachment picker listing attachments already linked to the target record for easy inclusion in outgoing emails.
mail.compose.message: Automatically enables the object attachment option for specific record messages (excluding mass mail) and limits selectable items to attachments belonging to those records.
mail.compose.message: When sending a single-record message, merges the selected object attachments into the mail values so the chosen files are delivered.