Anti-spam laws exist to prevent people from sending unsolicited, fraudulent or deceptive emails. That means, as a legitimate email marketer, you must be transparent about your company or organization and the purpose of your email messages. A valid postal address is one way to show recipients that the email is coming from a legitimate source.
TIP: Some content filters will also scan for an address and block or junk emails that don't include one, so it's also good for deliverability.
Adding your address to emails
A "physical address" means the mailing address for your business; a phone number is not required. It can be your current street address or a registered post office box (P.O. Box address).
It's best to add your company or organization name and postal address to your email template. If your template can't be updated immediately you can also add it directly to your campaign content.
The most common position for placement is the footer of your template (or the bottom of your campaign content) because that's where people will scroll down to look for it.
No set address, or no suitable address
For home-based businesses, it's understandable if you do not want to share your home address with subscribers. However, you must still supply an address; it just needs to be somewhere you can receive postal mail.
The same goes for professional artists (for example, painters, performers, dress-makers) who do not have an office or commercial address they can use. In order to avoid a potential fine for violating anti-spam laws, you may need to register and start paying for a P.O. Box. They can often be set up so you are billed quarterly, and the cost can be written off as a business tax deduction.