Cebull was found to have sent hundreds of offensive emails against blacks, Indians, Hispanics and women, the Judicial Council of the 9th U.S. Circuit Court of Appeals said in January.
He was charged under section 127 of the Communications Act of sending grossly offensive messages, which included racist taunts, to the former England player.
In this particular case, although the suspect admitted committing offences over a period of five months, he was merely cautioned for one offence of revenge porn and three of sending an offensive, indecent, obscene or menacing message.
Dallas, who is known to be close to McDonald, had been under investigation for the alleged sending of an offensive email relating to the pope's visit to Scotland.
Ben Townsend, 25, of Norwich Drive in Cheltenham, is accused of two counts of sending offensive messages under the Public Communications Act.
He had also been convicted of sending offensive letters to the families of Australian soldiers who had died in Afghanistan; a few days before the siege Australia's High Court had refused his bid to appeal against the conviction.
The self-styled Muslim cleric had also been convicted of sending offensive letters to the families of Australian soldiers who died serving in Afghanistan.
He was found guilty in 2012 of sending offensive and threatening letters to families of eight Australian soldiers killed in Afghanistan, as a protest against Australia's involvement in the conflict, according to local media reports.
Azhar Ahmed, 20, of Fir Avenue, Ravensthorpe, West Yorkshire, was found guilty in September of sending a grossly offensive communication.
McKenzie's resignation came in the midst of a crisis involving utility back Kurtley Beale, who is accused of sending offensive text messages about a team official.
