Hillary Clinton has come under withering criticism this campaign for setting up a private email server during her time as secretary of state.

But it’s not altogether clear that what she did was that unusual. While critics have said her decision to send emails over a private account allowed her to avoid public records laws, her defenders correctly note that scores of government officials also communicate outside of official channels.

Clinton loyalists got powerful new evidence to buttress their case last night. Before Wednesday’s presidential forum, House Democrats released an email that former Secretary of State Colin Powell sent then-Secretary Clinton, who had asked for guidance about using a private server.

House Dems just released email that Colin Powell sent to Hillary Clinton about using personal email at State. pic.twitter.com/CqSXwd3Lf8 — Rebecca Shabad (@RebeccaShabad) September 7, 2016

The email makes clear that Powell, too, used private systems to avoid the State Department servers — and for purposes that appear to be clearly related to his government office.

“What I did do was have a personal computer that was hooked up to a private phone line (sounds ancient.)” Powell wrote on January 23, 2009. “So I could communicate with a wide range of friends directly without going through the State Department servers. I even used it to do business with some foreign leaders and some of the senior folks in the Department on their personal email accounts. I did the same thing on the road in hotels.”

Now, there’s still a difference between Powell’s handling of the email server and Clinton’s. While it’s clear Powell used a private server to go around the State Department, he also did communicate over the State servers and maintained a State email account. By contrast, Clinton never set up a @state.gov account throughout her time as secretary of state and only used a private account.

But the distinction is increasingly looking like a matter of degree rather than kind. The torrent of criticism against Clinton is obviously connected to the extraordinary FBI investigation into her private server, but it also now looks wildly disproportionate given how close it mirrors that of her predecessor. And Powell doesn't just admit to using a private communications system to chat informally with his top aides: He even admits to doing so to talk directly with foreign leaders to avoid open records.

The email also is a bad look for Powell, who had earlier this campaign criticized Clinton’s people for “trying to pin” the FBI investigation on him. The 2009 email strongly suggests Clinton was telling the truth when she said she had sought guidance from Powell about setting up her private server.

At face value, evidence that Colin Powell has, umm, not been entirely honest about his advice to HRC. https://t.co/DImg35s5Px — James Fallows (@JamesFallows) September 8, 2016

At one point in the email, Powell tells Clinton “to be very careful” when skirting public records laws, adding he had done so “by not saying much and not using systems that captured the data.”

With Donald Trump trying to turn the server into a major campaign issue — and the media largely complying — Clinton is probably going to have to say quite a bit more about her email account. A new line she can add to her responses: Don’t necessarily trust Colin Powell’s advice.