I am trying to send plain text emails using the built-in email client (Emails → Compose).
If I do this, my signatures are messed up: line breaks are not implemented and ignored. Although the email displays correctly in the editor, when opened by the recipient, the signature is just one long line…
It affects the whole body of a plaintext email, not only the signature!
The solution seems to be:
As of version 3.0a1, forced_root_block is enabled by default. The documentation also saysthat if you disable this option, Enter will produce a <br />, while Shift+Enter will produce a <p>.
That change is not upgrade-safe. There are ways to redefine these values further up the call stack, possibly in upgrade-safe configurable portions of the code.
But I am afraid I can’t say exactly where, and I don’t have the time to investigate this now. Searching the code for tinymceSetup should put you on the right track.