I am seeing the following detail on my leads' activity reports on the soft bounce event. Does anyone know what that means exactly? I don't see anything wrong with the format of the from address...
"System send failure: DKIM signing error (Unexpected From address format in injectMessage '1 <1>')"
If you edit a draft of the email in Marketo, could you double-check that the From address is a valid address?
Are you using a token in From email, without any default email ID? If yes, please add a default email ID to fix this.