The controversial email was written more than nine months ago, but it is just now surfacing because one of the unions says it got the communication through a Freedom of Information request.
City workers and union leaders say they are insulted and are firing back.
"When a high-ranking city official calls workers 'totally useless,' I don't believe that's in line with our community values and has no place in San Jose," said city library employee Felipe Juarez at an afternoon news conference that highlighted a January email from San Jose Retirement Direct Russell Crosby to San Jose City Councilman Sam Liccardo.
In the email, Crosby referred to what he called, "?the 10 percent of the workforce that is totally useless and actually serves as a brake on forward motion by the rest of the workforce."
Union leaders say the comments overstep Crosby's administrative role.
"This email contains what I believe [are] very misguided feelings about employees. Serious enough statements that I believe makes it impossible for Mr. Crosby to continue effectively as the director of retirement services," said firefighters union president Robert Fabian.
Liccardo is out of town but issued a statement that read in part, "No one should condemn a dedicated and effective public servant, like Russell Crosby, without understanding the full context in which any statement is made."
Councilman Pete Constant, who Crosby also mentioned in the email, says it is the unions who are out of line.
"I think what's really objectionable to me is the fact that the unions are politicizing an email, and they know a process to take if they're concerned with a performance or personnel issue," said Stark. "Instead, they're going to the press."
Crosby did not return calls to ABC7 to clarify what exactly he meant in his email. But in a city politically charged with budget deficits and pension reform, city workers are taking the comments personally.
"I'd like to ask him, am I one of the useless? Am I one of the marginal? Is it time to skim me off the top like one of the 10 percent?" said crime lab specialist Phyllis Dawkins-Thames.
Both the mayor and the city manager issued statements Monday indicating this is a personnel matter, and if there is a complaint, the union certainly knows of the process to follow to lodge a complaint. The president of the firefighters union indicated that he will take formal action to request that the city manager fire Crosby from his job.