There are steps you can take to encourage respondents to complete your emailed survey.
Have a short survey
Keep your questions short and simple.
Don't ask too many open-ended questions.
Consider optimizing open-ended responses with audio input questions, and try to keep open-ended questions optional.
Show a progress bar in your survey so that respondents have a good idea of how they are progressing through the survey.
Use logic to show/hide specific questions, so that respondents only see questions that they need to respond to.
Personalize your survey
Use piped text to insert contact-specific data, such as their name.
Test your survey
Optimize your survey for all devices -- including desktop, tablet, and mobile views.
Consider testing with a small group before sending it out to your entire list of recipients, so that you can identify any design issues and get a general idea of your response rate.
Use Fatigue Protection
Don't give your contacts survey fatigue.
Enable Fatigue Protection on the global survey settings page to limit the number of emails a contact will receive over a specific timeframe.
By default, Fatigue Protection is set to 14 days, meaning that contacts will not receive more than one survey every 14 days.