A former male model-turned-elementary-schoolteacher sent out sexually explicit e-mails to potential hookups on Craigslist — but idiotically used a school e-mail account to do so, investigators found.

Upper East Side special-education teacher Matthew Maleski attached pictures of himself clad only in boxers to his e-mail responses to Craigslist’s notorious personal ads, according to officials.

The buff 32-year-old teacher, who was terminated from PS 183 on Tuesday, had formerly posed half-nude in ads for a gay social networking App called “Hornet.”

Maleski’s missives were uncovered because he used an account that he shared with a fellow teacher, who got disturbed enough by the content of the messages to confront him.

On Nov. 5, she told him she found at least five “e-mails that one could perceive to be inappropriate” on their shared account, which was intended solely for correspondence with families.

She told him she was bumping him off the account, and had already changed the password.

“[She] expressed that she was upset because, as she created the account, her name was associated with . . . Maleski’s inappropriate e-mails,” says a report by the DOE’s Office of Special Investigations.

Maleski, an untenured teacher who was hired by the Department of Education in November 2011, admitted to investigators that he had sent the salacious e-mails.

He also acknowledged that the attached photos were of him.

But he said he had sent the e-mails during non-work hours using his cellphone, which had automatically linked up a number of his e-mail accounts — including the one from PS 183.

The messages were sent on Sundays and early Friday mornings, investigators found.

“Those accounts must of [sic] interchanged accidentally,” he told his co-teacher in an e-mailed apology, according to the probe.

Investigators concluded on Jan. 14 that Maleski had “committed employee misconduct by sending inappropriate e-mail communications from an e-mail address that represents a DOE site.”

DOE officials did not immediately respond to a question about why it took them until this week — nearly two months later — to cut him loose.

They had redacted the titles of the Craigslist postings to which Maleski responded and also whited-out the content of his e-mails from their investigative report before providing it to The Post.

An agency spokeswoman said the redactions were made in order to protect the former teacher’s privacy.

A message left at a number listed for Maleski, who earned $56,000 per year in salary, was not returned.

He had formerly taught in other school districts in New York after getting certified to teach in 2004, according to state records.