salesperson.net is a valid email service that's been around since 1996 but the individuals using it may be suspect. There has been an increase in fraudulent usage recently.
Info below is from https://www.ipqualityscore.com/domain-reputation/salesperson.net
Is Salesperson.net a Suspicious Domain?
The mail domain salesperson.net is valid, has proper DNS MX records (mx01.mail.com), and is able to accept new email. Salesperson.net is a popular email service commonly used for personal account creation. An elevated amount of abusive accounts have recently originated from salesperson.net, which we would classify as a medium risk profile. Further checks are needed to validate users from this domain.