The inspector general's report noted that in October 2016, Comey spoke at the FBI's annual SAC Conference in San Diego, and noted that his investigators' view was "there really isn't anything here that anybody would prosecute" about Clinton's server.
But Comey added, "I have gotten emails from some employees about this, who said, 'If I did what Hillary Clinton did I'd be in huge trouble.'"
"My response is you bet your ass you'd be in huge trouble," Comey said in that speech.
"If you used a personal email, Gmail or if you [had] the capabilities to set up your own email domain, if you used an unclassified personal email system to do our business in the course of doing our business even though you were communicating with people with clearances and doing work you discussed classified matters in that, in those communications, TS/SCI, special access programs, you would be in huge trouble in the FBI," Comey said.
"Of that I am highly confident," he added. "I'm also highly confident, in fact, certain you would not be criminally prosecuted for that conduct."
The IG's report said that despite Comey's admonition to his then-subordinates, "We identified numerous instances in which Comey used a personal email account (a Gmail account) to conduct FBI business."
And the report also said that when asked about his own use of Gmail for official business, Comey said, "He did not" have any concerns about "conducting FBI business on his personal laptop or personal email."
Comey told the IG that his use of personal email was "incidental" and that "I was making sure that the work got forwarded to the government account, to either my account," or that of his chief of staff, James Rybicki.
"I wasn't doing classified work there, so I wasn't concerned about that," Comey is quoted as saying.
When asked by IG staff if his use of a personal email in such a way was in accordance with FBI regulations, Comey said: "I don't know. I think so, but I don't know. I remember talking to Jim [Rybicki] about it at one time, and I had the sense that it was okay."
The IG's report lists five instances where Comey used his Gmail account for bureau business.
They include his forwarding, on Nov. 8, 2016, to the Gmail account from his unclassified FBI account a proposed postelection message for all bureau employees.
The next month Comey forwarded to his Gmail account "multiple drafts of a proposed year-end message to FBI employees," according to the IG.
And "on December 30, 2016, Comey forwarded to his personal email account from his unclassified FBI account proposed responses to two requests for information from the Office of Special Counsel," the report noted.
"The forwarded email included two attachments: (1) a certification for Comey to sign; and (2) a list of FBI employees with information responsive to this request, including their titles, office, appointment status, contact information, and duty hours."
In January 2017, the report said, Comey forwarded to his personal email account an email that highlighted language that needed to be corrected in a Wall Street Journal article. And in March, he sent from that email account multiple drafts of his proposed opening statement to the House Intelligence Committee, according to the IG.
The report says that when asked about his use of personal email for agency work, Comey told the IG's office "I did not have an unclass[ified] FBI connection at home that worked. And I didn't bother to fix it, whole 'nother story, but I would either use my BlackBerry, must have been or Samsung...my phone, I had two phones—a personal phone and a government phone."
"Or if I needed to write something longer, I would type it on my personal laptop and then send it to Rybicki, usually I copied my own address," Comey said. "Yeah. And so I would use, for unclassified work, I would use my personal laptop for word processing and then send it into the FBI."
The IG report said, "given the absence of exigent circumstances and the frequency with which the use of personal email occurred, Comey's use of a personal email account on multiple occasions for unclassified FBI business to be inconsistent with the DOJ Policy Statement."