Dante Soiu told the Los Angeles jury he wanted his messages to show her unconditional love and friendship and that he had no animosity towards her over the earlier case, which sent him to a mental institution for several years.
That case involved 500 messages, including sex toys and pornography, that Mr Soiu sent Paltrow in 1999 and 2000.
Mr Soiu, 66, told the court he wanted to let Paltrow know he was available and willing to marry her if the opportunity arose.
His lawyers called him to speak in his own defence in the felony stalking trial.
He sent Paltrow 66 messages and packages between 2009 and 2015, but none of the recent correspondence included pornography. A judge has said the earlier messages could be important to understanding Paltrow’s fears.
Paltrow, 43, told the court on Monday that she was afraid of Mr Soiu and began crying when she expressed fears about her children’s safety.
Deputy district attorney Wendy Segall questioned why Paltrow would want to marry him after he had sent her so many lewd messages and she gave evidence against him.
“I was trying to show I had changed and I had become a different person,” Mr Soiu said. “I wanted to show a new face towards her.”
He said he did not want to scare the actress, but he was intent on her responding to him.
“I wanted her to say flat out ‘I don’t want to marry you’,” he said. “That way I would have a definite response from her.”
He said he wrote to many public figures, including US president Barack Obama, Israeli prime minister Benjamin Netanyahu, and Russian president Vladimir Putin offering counsel on world affairs.
He conceded that his notes to Paltrow were the only ones that expressed an interest in marriage. “Oh, no, I don’t want to marry Putin,” Mr Soiu said.
Mr Soiu was found not guilty by reason of insanity in 2000 in the previous case involving pornographic messages he sent to Paltrow. He was rearrested last year after sending the actress new correspondence.
He said he was addicted to pornography at the time but was now on medication and considered himself healed.
The recent batch of letters described Mr Soiu’s intention to marry the actress as well as a pair of earrings he sent her in 2009 as a Christmas gift, some secondhand clothes, and a Weight Watchers cookbook.