With applications due by 5 p.m. Monday, Secretary of State William Galvin on Monday cautioned people hoping to participate in the Sept. 6 primary elections against attempting to return vote-by-mail applications by mail and said to instead use either drop boxes or the online ballot application system available on his website.

"Your application to vote by mail in the State Primary will be honored as long as your local election official has it in hand by 5 p.m. today. If you drop your application into a mailbox now, it will not be delivered to your city or town hall by 5 p.m. today," Galvin said in a statement.

Voters can apply for a primary ballot up until 5 p.m. Monday at www.VoteInMA.com.

Also, in order for a state primary ballot to be counted, it must reach the voter's local election office by 8 p.m. on Tuesday, Sept. 6.

"The U.S. Postal Service typically recommends mailing a ballot no later than one week before Election Day. With the holiday weekend ahead and no mail delivery on Labor Day, there is no guarantee that a ballot returned by mail this week will arrive in time to be counted," Galvin's office said. "Voters who do mail their ballots close to Election Day should track their ballot's status at www.VoteInMA.com to confirm it reached their local election office by September 6 and was accepted. Voters always have the option of voting in person on Election Day if their ballot has not yet been received.