On the Futility of Write-Ins

You may want to write Sanders on the ballot this coming election but you would do better not to even vote.

Only 8 states allow voters to cast unrestricted write-in ballots. Eight. In 35 states the write-in candidate must file paperwork in advance of the election. And in seven states, write-in voting for presidential candidates is not even permitted. Of those 35 states a few may allow a write-in campaign to be organized by voters in support of a candidate who is not personally involved in running; the decision to allow this form of a draft campaign is left to each state’s municipality.

In close Presidential elections, write-in votes used to serve as a burden more than anything tactical. But today, modern polling places are prepared to ignore write-in votes using the most advanced technology available. Optical scanning machines are preprogrammed to automatically "kick out" write-ins from the computer's running tabulation. The machine then literally spits the write-in ballots into a pile on the floor. County polling representatives "sort" through the pile later.

Source: NASS STATE LAWS REGARDING PRESIDENTIAL BALLOT ACCESS FOR THE GENERAL ELECTION

A populist draft campaign for Sanders isn't going to produce positive results.