The cover addressed to "Master" Jack G. Rutherford, suggests he was a child. I checked the 1940 US Census and sure enough, a Jackson G. Rutherford was a member of the Rutherford family, age 22 at that time, which would have meant he was born around 1918, making him about 10 years old at the time the cover was postmarked in 1928.
As a young child, I remember receiving mail from a distant family member using the term "Master" ... and I hated it. I just looked up the reference of using that term as an address and came up with this:
Quote:
The style "Mr." or no style at all is usually used when addressing boys today.
The use of Master as a prefixed title, was according to Leslie Dunkling, "until recently ... a way of addressing politely a boy who was too young to be called "Mister".
Robert Hickey, deputy director of the Protocol School of Washington, states that "use of Master [as] an honorific when addressing boys is considered old fashioned outside of conservative circles."
Nancy Tuckerman of the Amy Vanderbilt Complete Book of Etiquette writes that a boy can be addressed as master until age eight, then is addressed only by his name with no title until he turns 18, when he takes the title of Mr., although it is not improper to use Mr. if he is slightly younger.