mail_notification_custom_subject

Purpose

Allow customizing Odoo notification email subjects through configurable templates per model and subtype.

Features

mail.message.custom.subject: Lets admins configure subject templates per model and message subtype using placeholders and choose whether to replace, append before or after, or partially replace existing subjects.
mail.thread: Applies matching subject templates when posting messages and skips replacements if a subject was explicitly provided.
mail.thread: Builds a default subject prefixed with "Re: " and the record name when no subject is set before applying templates.
mail.thread: Processes multiple applicable templates sequentially so appended fragments can accumulate around replacements.
mail.thread: Logs template rendering errors and keeps the original subject instead of blocking message posting.
settings: Adds a Technical > Email menu action for managing subject replacement templates with dedicated form and list views.