To add custom voting buttons in your email messages in Microsoft Outlook, please do as following:

1. Create a new email message with clicking Home > New Email.

2. In the new Message window, go to the Options tab, and click the Use Voting Buttons > Custom.

3. In the popping up Properties dialog box (or Message Options dialog box in Outlook 2007), remove original voting options from the Use voting buttons box, and then enter your custom voting options. See screen shot below:
Notes:
(1) You can add as many voting options as possible, and keep in mind to separate each voting option with the semicolon.
(2) Keep the check box before the Use Voting buttons checked all the time.

4. Click the Close button to exit the Properties dialog box.

5. Compose your email message, and then click the Send button.

When recipients receive your email message with the custom voting buttons, they can click the text of Click here to vote. in the message header and then specify a voting option from the drop down list. See screen shot below:

If you receive recipients’ voting responses, you can view the voting responses at the message headers at a glance.

Note: The customized voting button is only applied to the current message. When you create a new message, the voting button you have customized is disappeared, so you need to customize a new voting button for the message if you want.

As you know, the voting buttons are single-choice and shown in message header with above method. However, sometime you may just want to add the voting buttons in message body. Here, this method will introduce Kutools for Outlook's AutoText feature to insert checkboxes in message body as voting buttons.

1. In the Mail view, click Home > New Email to create a new email.

2. In the opening Message window, click Kutools > Pane to activate the AutoText pane, open the CheckBox category, and then double click the Checkbox 1 to insert it into message body. See screenshot:

3. Repeat above Step 2 to add more checkboxes, and then rename the checkboxes to your voting options as below screenshot shown.

4. Compose your email message, and then click the Send button.

Note: When recipients receive this email with multiple-choice voting buttons in Outlook, they need to (1) click Home > Reply, (2) check multiple voting buttons as they need, and then (3) send the replying email.

By the way, if the recipients read this email with other mail tool, such as read the email with web browsers or smart phones, the checkboxes are not clickable.