I'm receiving a weird error while sending messages on 8.4.0. The messages still send regardless of the error.
The error comes from save_msg(async) in dada_mail.js. The AJAX request fails all the time and inspection of what is being returned from the AJAX call indicates that there is an error.
Checking the error log doesn't show anything related to saving other than "Identity is invalid. Must be a verified email address or domain."
Unlike issue #516, multiple list sending is disabled but AWS is enabled. Batch settings are done manually too.