The father of a 17-year-old youth complained to police that the teenager received a text message on his phone offering to supply him with cannabis.
It gave details of the cost and the arrangements for picking the drug up.
The seller, Colin Porter, was traced and his home in Brookthorpe Close, Warndon, Worcester, was searched.
Officers found scales, plastic bags and 70.63 grammes of cannabis, said Jo Barker, prosecuting at Worcester Crown Court. He pleaded guilty to possession of cannabis with intent to supply and allowing his home to be used for smoking the drug.
Porter, a 43-year-old home delivery driver, was given a 15-month prison sentence in 1992 for drug supply.
Jailing him for another eight months, Judge John Cavell said he held attitudes about cannabis which were in conflict with the law.
He said the father's complaint exemplified the harm done by drug pushers.
Before Porter was caught he sent the teenager another text saying he was at home and the drug was available at his flat.
Porter denied sending the texts but admitted supplying a circle of friends to fund his own habit.
Jason Aris, defending, explained that Porter used cannabis to combat health problems caused by a spell in the Foreign Legion 15 years ago.
He suffered from post traumatic stress disorder and an arthritic shoulder.
At the time he was caught he was on disability allowance and paying off debts. Since then, he had found a job with a Blackpole firm which was aware of his offending and promised to keep his employment.
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