How to set up an auto reply/out of office in Apple Mac Mail (OSX)
Whenever you go away from your computer for an extended period of time, you should probably set up an auto reply in your mail client to avoid people with pitchforks emailing you over and over again waiting for a reply, when in fact you aren’t even there. Below is an easy to follow step-by-step guide which will explain how to add an out of office to your Apple Mail client.
Step 1:
Open Apple Mail.

Step 2:
Click on Preferences, Rules.
Step 3:
Click the Add Rule button on the right.

Step 4:
In the description, type the name of the rule, such as “Out of Office”. Ensure that the rule is applied to “Every Message”. Also make sure that the action performed is “Reply to Message”. You can then click on “Reply message text…” and fill in the text that you want to automatically reply to people who email you whilst you are away. Example: “Thanks for emailing me. I am currently away until <date>. If your matter is urgent, please email colleague@yourdomain.com.
Once you are done, click OK.

Step 5:
This is an important step that can potentially make you look very silly, so pay close attention. At the next screen, a message will pop up asking you “Do you want to apply your rules to messages in selected mailboxes” you want to chose “Don’t Apply“. If you were to click on “Apply”, it will send an out of office message to all the emails that are currently in your mailbox, and you don’t want that, otherwise you will have some angry people on your hands. You only want to apply this rule to new emails that you receive, so make sure you click “Don’t Apply“.

Your rule will now be running every time you receive an email, until you turn it off. To turn it off, go back into Preferences, Rules and untick the checkbox next to the rule for Out of Office.