matcher tag: more flexible operators

[chibenwa]

Today the following label onto the mailet tag are permitted:

• match includes only recipients matching the condition
• notmatch includes only recipients not matching the condition

While this is enough for 99% of the use cases we may encounter use cases where we are limited:

For our AI mailbot integration we want to ingest the email into the GPT chain if at least one of the recipient is [email protected]. This forced us to write https://github.com/linagora/tmail-backend/blob/master/tmail-backend/tmail-third-party/open-ai/src/main/java/com/linagora/tmail/mailet/RecipientsContain.java

Instead we could have generic mailet tags allowing to augment existing matchers:

• all_match: condition needs to be satisfied for all recipients
• at_least_one_match: return all recipients if one matches
• no_match: equivalent to not at_least_one_match and ensure no recipient match this all

Modification can be done in https://github.com/apache/james-project/blob/d43cfea12cd3e8db556edf84c06fc7e555ad940d/server/mailet/mailetcontainer-impl/src/main/java/org/apache/james/mailetcontainer/lib/AbstractStateMailetProcessor.java#L227

Recorded as an idea for easy contributions, eg for OktoberFest