Adding an "Out of Office" reply message to your email account is an important step in letting people know you are away and may not be able to respond to them as you otherwise might

To setup an Out of Office reply that automatically responds every time someone emails you while you are away:

1. In Gmail, click on the cog (or gear) icon in the top right-hand corner
2. Select Settings from the drop-down menu
3. Scroll down to the bottom of the Settings page under the General tab to find the Out of Office auto reply section
4. Turn on “Out of Office AutoReply” by selecting the option
5. Enter your subject and message, adjust the dates to suit and finally press the Save Changes button

Make sure you correctly set the dates for the start and end of your absence  to ensure your replies are not continuing to be sent after you have returned.