A group of friends have told how they received mysterious personal emails from their friend's account five months after he died suddenly of heart arrhythmia.

The messages referred to private conversations and personal events that happened just before the young man's death, the BBC reports.

Jack Froese died in June 2011 at his home town of Dunmore, in the US state of Pennsylvania.

In November three of his friends began receiving emails from his account.

"One night in November I was sitting on my couch going through my emails on my phone and it popped up — 'sender' Jack Froese," friend Tim Mark said.

"I turned ghost white … It was very quick and short but to a point that only Jack and I could relate on."

The email, titled 'I'm watching', read: "Did you hear me? I'm at your house. Clean your f---ing attic!!!"

Mr Mark said shortly before Mr Froese's death the pair had climbed up to his attic to survey the dusty floors and determine how much clean-up work was required.

Another email sent to cousin Jimmy McGraw from Mr Froese's account referred to Mr McGraw breaking his ankle and said: "I tried to warn you, gotta be careful".

One friend emailed the account back but did not receive a reply.

The friends do not believe the messages are from beyond the grave, but they have decided it is not important to identify the sender.

They said the emails have helped with the grieving process.

Mr Froese's mother Patty encouraged the friends to accept the mysterious emails as a gift.

"I saw it made people happy, upset some people, but to me that's keeping people talking about him," she said.