When you are not in the office, you can set up an auto-reply message telling senders when you are going to be back and the persons they can ask for help. If you work with Gmail, please see here to set up an auto-reply message.
Step 1: Click the "File" tab from the ribbon;
Step 2: Click "Automatic Replies" button;
Step 3: In the "Automatic Replies" window:
1. Check "Send automatic replies";
2. Set up the "Start time";
3. Set up the "End time";
4. Type the message in the message box "Inside My Organization";
5. Format the message.
Step 4: Click "Outside My Organization" tab and copy the same message to the message window (or type a new message to share with senders outside of the organization);
Step 5: Click "OK" at the bottom.