A netmail message would contain the name of the person sending, the name of the intended recipient, and the respective FidoNet addresses of each.
From the en.wikipedia.org
Most BBSes, including those that are now available for users with Internet connections via telnet, also retain their FidoNet netmail and echomail feeds.
From the en.wikipedia.org
More examples
E-mail: communicate electronically on the computer; "she e-mailed me the good news"
M+NetMail is an ISP-grade E-mail package by Messaging Architects. It is designed to deliver scalable messaging and calendaring services, using Internet-standard protocols (e.g. ...