Copy of signed agreement not being emailed to signer.

After a document has been signed by a customer it states that a copy will be sent to all parties, however it isn't sending a signed copy to the signer after they sign and complete the agreement. I have tried testing it with multiple people and no one is receiving them, so I don't think the messages are getting caught in SPAM or anything. I feel like I've double checked everything, but are there any settings I possibly need to change?