Reminder emails are a great way to boost participation in your poll, so long as you do not send so many that it annoys your voters. We usually see a spike in votes being cast every time a reminder is sent.
You can schedule reminder emails on the Mailings tab of your active poll.
With any paid subscription, you can send as many reminders as you think is appropriate, keeping in mind that if you send too many, you risk annoying your voters. (Free accounts can send a limited number of reminders.)
The total number of recommended reminders will depend on a variety of factors, including the length of the voting period, the total number of voters, and how eager the voters are to participate. We do not allow emails to be broadcast to your voters more often than every 24 hours, and we recommend that you have at least two days, if not longer, between reminders.
As a general rule of thumb, if you have a poll that will be open for 3 weeks, we would ordinarily recommend that you send the initial invitation to vote when it opens, a reminder after one week, and again after two weeks, and then a final reminder, potentially, the day before the poll closes.