Joseph Lai Chi-shing, 51, had pleaded guilty to three counts of criminal intimidation.

Eastern principal magistrate Ada Yim Shun-yee said Lai had used a "very wrong" way to express his dissatisfaction.

The court earlier heard that Lai suffers from Asperger's syndrome and obsessive-compulsive disorder, for which he has been receiving treatment and medication since 2013.

Prior to taking aim at Lam, Lai had also threatened others with violence and arson.

According to court documents, Lai is advised to receive psychiatric therapy so that he may be rehabilitated and "participate in appropriate social responsibilities."

The threats began on March 4 this year when an employee of the Hospital Authority received an email from Lai in which he stated his intention to "kill Carrie Lam."

In similar emails to another government employee on March 21, Lai said he would "kill Lam'' or else he will "blow up the government headquarters and the Immigration Department."

Eight days after those emails were sent, Lai was arrested. While in custody, he told police that he sent those three emails because he was "very angry" and "did not like" Lam's Covid-19 policies.

"I was displeased with the Covid measures introduced by Carrie Lam," Lai said. "I just wanted to complain."