[meeting] 2025-07-29 core mailer beta planning

During July, most of the work went into defining and discussing the user stories recorded in #3534136: Requirements and strategy for Core Mailer. The group agrees that these user stories and their acceptance criteria adequately cover the problem space. However, user stories in groups B (context switching safe defaults) and C (security) appear to conflict with each other in certain circumstances. Additionally, the user stories in group C need to be extended to include security issues that have already been fixed in contrib.

There has been a proposal to use a tandem of config entities and plugins for the mail building part (#3536575: Introduce EmailTemplate config entity and plugin type and #3536579: Use EmailTemplate config entities in core modules). It was dismissed due to risks associated with recipes (config is not installed by default).

The proposal sparked a discussion on how the group should work on finding a solution for the mail building. Some members would prefer to spec out the system before it is built. Others need to see code and play with it end-to-end before they like to commit to a specific approach.

It was proposed that the group should seek feedback from the community to identify the pain points of the core and contrib options currently in use.

A high level architecture overview has been drafted which will be refined in the coming days.

Next planning meeting takes place September 3rd at 4PM UTC+2.