The Dui Hua Foundation circulated copies of two court documents for the first trial and appealed the sentence of Gonpo Tserang, 32, in the Dechen TAP.
The verdict from the initial trial said, "defendant Gonpo Tserang used the internet to deliberately fabricate rumours, distort the true situation and incite separatism."
The court documents listed six people based abroad who were alleged to have received the email messages from the defendant.
They also linked the case to the "March 14 incident," referring to a violent uprising against Chinese rule last year by Tibetans in Lhasa, the capital of China's Tibet Autonomous Region.
The appeal document was dated January 5, 2009, with the delay in any public reports on the trial apparently a result of the customary secrecy surrounding such cases in China.
Dui Hua said the case involved the only known conviction of a Tibetan in Yunnan on a charge linked to state security.
"The content of the messages is never specified, and it is questionable whether individuals who are not located in China are even capable of carrying out acts that would 'split the nation or undermine national unity'," Dui Hua said in a statement.
Gonpo Tserang was apparently not represented by a lawyer, at least at his appeal hearing, it said.
China holds many such trials in secret, with judges often taking just minutes to approve state prosecutions, and government-run media often carry no reports of the verdicts.
More Tibetans were reportedly sentenced in Sichuan province, which borders Yunnan and the Tibet Autonomous Region.
Founded by US citizen John Kamm, a former businessman, Dui Hua has lobbied China for the past 18 years to reduce individual sentences or release prisoners jailed in cases linked to abuses of human rights.