Saving incoming msg object to reply later (Serialization Error)

[joinlook]

@p.colbert

In order to reply, you probably don’t need to save the entire message, just the “from” and “subject” parts. (But you might want to save the whole thing for reference later.)

I tried this but it would still reply from a new thread. It would work if there was a header argument such as anvil.email.send(.... , headers=[("In-Reply-To", message_id)]).

I wanted to use only anvil.email, but in the meantime using sendgrid works by means of message.header = Header('In-Reply-To', 'message_id', p=1)

Am I missing something simple with the anvil email service?