Thanks for adding it over there, @WofWca . From my user perspective this stirred up a hornet’s nest on arbitrary limitations to be added, instead of safe-keeping the ability to handle classic e-mails.
There have been similar changes in the past, such as removing the option to have a separate folder when using Chatmail with a traditional email account. I deeply regret all of this, and I’m afraid no one cares. m2c
PS: The issue was not about long messages get converted (now marked as duplicate of #7718) but that auto-resent messages are send truncated, not original. Anyway, it is what it is. Again thanks for adding an issue from my user side of things to the developers I have a hard time to keep up with just language wise.