It should inform key colleagues that you will be taking the day off, whether or not you will be active during your sick day and how they can proceed while you are away.
Anxiety attacks or episodes of depression. Include the date s of your absence as well. Some managers — and companies — prefer that you send a note about your absence to your team, and not just your direct boss, so that all your colleagues are aware that you're unavailable.
I plan on taking an unpaid day off to rest up and get better.
Also, if you have a hunch you'll need more than one day out, make sure you address that in your email and let your manager know that you'll follow up about your state.
You can leave the date and contact information out of the top of the message. Should you set an out of office message? Whether you plan on taking a paid or unpaid sick day.
The last thing you need is to be judged for careless mistakes or typos. You can also provide your phone number, in case something urgent comes up.