At any given time, hundreds of postcards are in transit across the world as strangers communicate through a movement called Post-crossing. 

Emma Delaney says it's a sad day when there isn't a postcard in her mailbox. She doesn't have a bunch of friends travelling overseas at the moment ---- she's just really active in the underground hobby of Postcrossing. 

"I've sent over 3,000 postcards, but I've been doing it for close to seven years," she says. "My husband, generally appreciative of my hobby, is sometimes frustrated by the amount of cardboard hanging around the house or in my car." 

Postcrossing is a hobby where strangers send each other postcards across the world. You register on the website, list your interests and preferences for postcards, then receive an address of a stranger on the other side of the world to send a postcard to. 

"I tend to send a lot of postcards of the local area because people are interested in where you're from and what you do," Emma says. 

From Uzbekistan to Belarus and Kazakhstan to Moldova, Emma has a growing collection of photos from around the world. The postcards have helped shape her international travelling too. "I didn't travel overseas until I was 32 and a lot of the locations we chose for our honeymoon were selected because of the postcards I'd received." 

"Some people see sending mail as being a bit boring and unfashionable, but Postcrossing is popular and lots of people are fascinated that I do it.," 

The Postcrossing project has just celebrated its eighth birthday and has over 400,000 active members in 215 countries. The group says they've delivered over 18 million postcards. 

And while postal workers aren't supposed to read people's postcards, Emma says she's happy for them to do so at her post office in Shellharbour. She even encourages her correspondents to say hello to the Australia Post staff. 

"It's a hobby that I continue to do because I find it enjoyable and relaxing."
Who gets sad when there isn't a postcard in her box?
Is she single?
What does she do for fun?
What's that?
Do they ever meet each other?
Does her spouse ever get annoyed?
Why specifically?
How old is he?
How many are involved in this activity?
In how many nations?
Who isn't allowed to view the messages?
Can an exception be made?
For who?
Will she keep on doing this into the future?
Why?
Can you estimate how many messages there are in the system at one time?
Emma Delaney
Emma Delaney
No
"My husband, generally appreciative of my hobby,
Postcrossing
 Postcrossing
strangers send each other postcards
strangers send each other postcards 
No
You register on the website, list your interests and preferences for postcards, then receive an address of a stranger on the other side of the world to send a postcard to.
Yes
 is sometimes frustrated by the amount of cardboard hanging around the house or in my car.
by the amount of cardboard hanging around the house or in her car
by the amount of cardboard hanging around the house or in my car
unknown
unknown
400,000
400,000
215
215
postal workers
postal workers
Yes
She even encourages her correspondents to say hello to the Australia Post staff. 
post office in Shellharbour.
post office in Shellharbour.
Yes
that I continue to do because I find it enjoyable and relaxing."
she finds it enjoyable and relaxing
find it enjoyable and relaxing
No
The group says they've delivered over 18 million postcards. 