The card was posted during King Edward VII's reign
The card was sent from a woman called Jane and addressed to a Miss Riley of Richmond Road, Heaton Mersey, near Manchester.
The sepia card still bears the halfpenny stamp showing the head of King Edward VII, who reigned from 1901 to 1910, but the postmark is unreadable.
Katy Russell, 31, found the card when she went to collect her morning mail.
It read: "Dear Joyce, Thank you so much for the letter. Cousin John came for tea (Sunday).
"Florrie and I took him to the car about 11 o'clock (shocking wasn't it).
"I hope S. E. and W are better. I am sorry they are not well and also Alice Ann.
"It is a pity so soon after the holidays. With much love to all, Jane."
A Consignia spokesman explained it was unlikely the card had been stuck in the postal system until now.
"The most likely explanation for this is that the postcard was part of a collection and was discovered at a property, discovered hidden away somewhere," he said.
"Someone may have thought it was still current and put it in the post.
"All our systems have been updated, we have moved buildings, there is virtually no chance of this being found hidden in our system."