Hillary Clinton's State Department for years was telling underlings not to use personal email -- even ousting an ambassador, the ex-diplomat says, in part over his Gmail habits -- despite the secretary of state herself ignoring that advice. 

The disconnect is now raising questions of a double standard during her tenure. 

An internal 2011 State Department cable, obtained by Fox News, shows Clinton's office told employees not to use personal email for security reasons. 

A year later, then-U.S. ambassador to Kenya Scott Gration resigned amid a series of clashes with the department, including over email. 

"My experience was somewhat different than Secretary Clinton's use of her commercial account, yet I was 'fired' for the use of Gmail in the US Embassy, my insistence on improving our physical security posture, and other twisted and false allegations," Gration told FoxNews.com in an email Friday, while adding: "I've chosen to move on and to be better, not bitter." 

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Gration's departure from the Obama administration was far more complicated than the matter of his email use -- he was cited for his allegedly aggressive management style and other infractions, though he disputes some of them. But a scathing inspector general report repeatedly censured him for his personal email practices -- underscoring how frowned upon the use of non-government systems was. 

In addition, Gration claims he only used Gmail "for unofficial business and for my personal emails," and his official emails were "fully captured in the State Department data bases." 

By contrast, Clinton simply stayed off the government system and used personal email -- for virtually all business. 

She handed over thousands of emails when the State Department sought them after the fact, and now says she has asked the department to make them public. Her representatives say the "letter and spirit of the rules" allowed the use of non-government email if records were kept, and deny any effort to skirt the system. 

Based on publicly available policies and the 2012 inspector general report, however, this was not the standard applied to other officials. If nothing else, it raises transparency questions for Clinton that could hang over her political future as she nears a likely presidential run. 

Rep. Mike Pompeo, R-Kan., suggested Clinton was following a different standard, invoking her infamous quote before a congressional committee about the controversy over the origin of the 2012 Benghazi attack. 

"We're now starting to begin to see when she told Congress awhile back 'What difference does it make?' She wasn't talking about the four dead Americans in Benghazi, she was talking about herself," Pompeo told Fox News on Thursday. "What difference does it make if you comply with the requirement to tell the American people everything you know? What difference does it make if you tell everyone in the State Department that they've got to have an official email account but you don't have one?" 

The 2011 State Department cable, sent to diplomatic and consular staff in June 2011 and bearing Clinton's electronic signature, made clear to employees they were expected to "avoid conducting official Department business from your personal e-mail accounts." The message also said employees should not "auto-forward Department email to personal email accounts which is prohibited by Department policy." 

It cited a section from the Foreign Affairs Manual, which states: "It is the Department's general policy that normal day-to-day operations be conducted on an authorized AIS [the authorized department information system] which has the proper level of security control to provide nonrepudiation, authentication and encryption, to ensure confidentiality, integrity, and availability of the resident information." 

Gration, a former Air Force fighter pilot, offered an explanation for why he took issue with the department's cyber policies. 

For instance, he questioned why he was "prohibited" from sending a Gmail message to a State Department computer in most cases, since other official accounts used the "same routers and security firewalls as a Gmail account." 

He said he ultimately used that account to access personal emails and alerts, which were not available on the official system. He acknowledged some of the findings in the IG report but called others "misleading" and "falsehoods." He said it was "false" that he "willfully disregarded" the department's commercial email policies, since he used the official system for much of his government business. 

The wide-ranging report included myriad accusations about his management style -- including an alleged practice of "publicly berating" staffers and personally "attacking" them. The IG report cited deteriorating morale under his "divisive and ineffective" leadership. 

Asked Thursday about the 2012 resignation and report, and how Gration's email practices compared with Clinton's, a State Department official gave a general response: "In the summer of 2012, Ambassador Scott Gration offered his resignation as Ambassador to Kenya. Shortly after, the State Department's independent Inspector General issued an August 2012 inspection report citing several concerns with management and leadership at our embassy in Nairobi." 

Gration now works at a private firm in Kenya. 

FoxNews.com's Judson Berger and Fox News' Catherine Herridge contributed to this report.