If you are seeing confirmation emails being generated by Soapbox Engage apps after an action is taken by a visitor - submitting a donation, registering for an event, signing a petition, purchasing through a Shop store - that only include the word "Array" in the email body, it is likely due to the fact that a pipe character (i.e., |) is included in text of your email.
If your email confirmation text includes this character, replace or remove it and run a test to confirm that this resolves the issue. If not, please open a ticket with details and we'll be happy to investigate!