She had reached the end stages of a terminal disease only to be saved by the donation of lungs from a woman she knew little about, but who in death had literally breathed life into somebody else.

So when she arrived home in Gladstone, Mrs Slatter penned a letter.

She wrote another at three months, another at six months, another on the first anniversary of her operation and letters at Christmas and Easter.

"I told my husband I'm going to keep writing until they tell me to stop, and they never did," Mrs Slatter said.

"I tried to say how grateful we were, because I was dying. 'Thank you' didn't seem enough to me. That word 'thank you'. What they gave me, no gift could compare to that."

Each letter carefully omitted any identifying information in accordance with government guidelines, but Mrs Slatter always left hints that she wanted to be found.

And then one day in May she was sitting at home when the phone rang, with two women on the line asking questions so personal that Mrs Slatter suspected a prank.

"Then all of a sudden one of the girls said, 'You wear a locket around your neck', and I went, 'Yeah ... why?' and they said, 'Because you've got our sister's lungs'. They started crying, screaming, we were all pretty emotional."

The donation authority does not encourage organ recipients and donor families to make personal contact, although it supports recipients to write anonymous letters that are checked and forwarded on.

Medical professionals are prevented by law from passing information to their patients about their donors, and they are not given the donors' identities anyway.

But the internet has given donor families and recipients easy means to find one another if they wish to do so, and many of them do.

St Vincent Hospital's medical director of lung transplantation Allan Glanville said the guidelines were to protect the privacy of donor families.

"You can find out information if you really want to," Professor Glanville said.

"Anybody who received a transplant will know really when the original donor died. There are death notices. There are things on social media. Often there might be a story in the media. So people do do this, but it's not at our recommendation."

On the day Mrs Slatter received her phone call, Suzie and Thuy Nguyen had been reminiscing about their sister Aileen, who died after a fight with depression 14 months earlier.

Although they had never replied to Mrs Slatter's letters, each time they arrived the Adelaide family would gather together for one of Aileen's daughters to read them out.

On a whim, they decided to find her and 90 minutes of googling they found a local newspaper story about a women who matched all the details they knew about their sister's lung recipient.

"We were jumping up and down and screaming 'Oh my God, oh my God'," Suzie Nguyen said. "Two minutes after finding the article I picked up the phone and started dialling without thinking."

The families began a friendship that culminated in their first meeting in Melbourne last week.

"My sister's lungs were inside Tracey, and first meeting her, my heart started thumping," Suzie Nguyen said.

"It was almost like a dream."

For Mrs Slatter, the meeting brought closure, but also the sense of a new beginning.

"The connection was so amazing and so close," she said. "They're looking to come up here. They want to go crabbing, fishing, camping. The two families have become one family."

Nearly a quarter of donor families did not receive any correspondence from the recipients even though they chose to, according to a 2014 survey by the Organ and Tissue Authority.

Among those families who did receive a letter, 87 per cent found it to be "of great comfort".

Recipients can pass letters to their hospital's transplant co-ordinator, who sends them to Donate Life to forward to donor families, with each check point scrutinising the letters for identifying information.

Transplant Nurses Association president Christine Ellis said the de-identified system also protected transplant patients, who were often distressed to learn how their donors had died.

Older patients did not want to know their organs or tissue had come from children.

"We've had young teenagers who commit suicide and if you were 50 years old with a child that age, that would be exceptionally distressing for you," Ms Ellis said.

More occasionally, donor families did not approve of the person who had received the organs.

But Donor Families Australia co-ordinator Bruce McDowell said the system was so convoluted that it was not uncommon for organ recipients to learn their letters had not been forwarded to the donor family.

"A lot of recipients are saddened to learn that they've written a card and it hasn't gotten through," said Mr McDowell, whose 19-year-old daughter donated tissue after she died in a car crash seven years ago.

"We've had nothing from recipients and I can tell you my wife and I would have loved to have had something, to have had a thank you.

"I know from recipients how hard it is to write that letter and I take that. But it would be nice. I've seen many families who get that letter and they frame it."

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