Tuesday is election day for cities across the commonwealth, and the secretary of state has some words of warning and advice for voters.

Secretary of State Bill Galvin held a press conference at the Massachusetts State Library on Monday to warn voters against mailing ballots back, since local elections have different rules than statewide contents.

“I am greatly concerned however, that there is some misunderstanding about the return of vote by mail ballots. In the case of municipal elections, the way the statute was passed, there is no grace period, so ballots must be received not later than the close of polls tomorrow,” Galvin said.

Along with a number of other provisions, the VOTES Act, signed into law by former Gov. Charlie Baker, allows all voters in Massachusetts to vote by mail with no excuse required. However a large number of voters who elected to receive a mail ballot, Galvin said, are still holding onto them, despite there being different rules.

“At this present moment, literally tens of thousands of ballots are as yet unreceived, that is to say they are apparently still in the custody of the voter,” Galvin said.

Town drop boxes and town elections offices will accept mail-in ballots on election day, Galvin said, and voters who cannot physically deliver their ballots are allowed to have them handed in by a family member. Ballots not received by the time polls close cannot be counted, Galvin said.

“It’s very important that these ballots are counted. These people took the time to participate. I want to make sure their ballots are counted,” Galvin said.

According to the Secretary of State, the timing of municipal elections is up to individual cities. Most run their elections from 7 a.m. to 8 p.m., but Agawam, Chicopee, Franklin, Methuen, North Adams, Pittsfield, and Westfield have slightly different polling hours.

Galvin said he expects less turnout than in 2021 — especially in Boston, where there is not a mayoral contest this cycle — but stressed the importance of these local elections. Less than half of voters will participate, Galvin said, despite the direct impact the elections will have on their daily lives.

“The way our government is structured in Massachusetts, local government has a great deal of authority in a number of areas: education, taxes, development, housing, planning, zoning. And these decisions are really reflected by decisions made by voters in the municipal elections,” Galvin said.

Galvin said he expects turnout to hover between 30% and 50%. Some municipalities, like towns and cities in the Worcester and Hampden state senate district, where there is a special election, have shown especially strong vote by mail participation, Galvin said.

Galvin said he’s not satisfied with those turnout numbers — he’d like to see everyone vote, he said — but he’s happy to see there are some local races garnering significant attention.

“These races are significant,” he said. “This is where our communities, historically, have made their decisions.”