Ed is a person Max has an email from on her computer. It appears they have had several correspondences but the nature of their emails is unknown. It seems the first part of the email reads, "Thank you for ordering...."
It is believed that Ed has conducted several private sales with Max, however the details of her purchases are unknown. It is likely to be photography-related equipment, considering Max's expenditure on old film for her instant camera. This is backed up by the fact that this email contains the keyword "camera".