Description

As @micheh reports, since #44732 it's more complicated to add an In-Reply-To or References header, since you have to take care of the brackets <...> yourself, see #44732 (comment)

• I could try to create a PR for something like ->addRelaxedIdHeader() that adds the brackets, but doesn't validate the content
• Or I could just document the status-quo and tell people to add the brackets themselves: https://symfony.com/doc/current/mailer.html#message-headers

What do you think?

Example

No response