Put an address in your email signature when the law, or the people you write to, expect one. For most people writing to colleagues and clients, name, role, phone and website are enough. Two cases change that: US email whose main purpose is selling needs a valid postal address, and UK companies show their registered office address on business letters. Shops, clinics, offices and anyone people visit in person often add one too, because it saves a "where are you?" reply.
When the law asks for an address
United States, commercial email. The FTC's CAN-SPAM compliance guide says: "Your message must include your valid physical postal address." That can be a street address, a post office box registered with the US Postal Service, or a private mailbox registered with a commercial mail receiving agency. The law "makes no exception for business-to-business email."
The rule follows the message. It covers email whose primary purpose is advertising or promoting a product or service. A reply about an order already agreed is a transactional message and is largely exempt. Our CAN-SPAM guide explains where the line falls. A signature is a convenient place to keep the address, because it then goes on every email by default.
United Kingdom, companies. Regulation 25 of the Company, Limited Liability Partnership and Business (Names and Trading Disclosures) Regulations 2015 says a company must show the part of the UK it is registered in, its registered number and the address of its registered office on its business letters, order forms and websites. The registered office is the address on record at Companies House, which can differ from the office people visit. Our UK company email guide covers how that applies to email.
Other countries have their own rules. The compliance guides cover the US, UK, EU and Canada in plain language.
Which address to use
- The office people visit, if you have one and want visitors. One line, the way you would write it on an envelope.
- A PO box or a registered private mailbox, if you work from home and the address is only there for CAN-SPAM. The FTC guide accepts both.
- The registered office, for a UK company's legal line. Put the registered number and the place of registration with it, for example "Registered in England and Wales No. 01234567". Those three details are the same for everyone at the company.
Skip the address when no rule asks for one and nobody visits. A home street address in every email goes to everyone you write to, and to everyone they forward it to.
How to add the address line
In Gmail, Outlook and Apple Mail, type the address as one more line in the signature box, under the phone and email. Keep it on one line and in the same or a smaller size than the rest, so it reads as a detail. The install guides cover each mail app: Gmail, Outlook and the full list.
Since October 22, 2026, Signatoro, the agentic email signature platform, has an "Address" field on every plan, Free included:
- Open Signatoro's generator, or your signature page if you have an account.
- Type the address in "Address", up to 200 characters.
- It shows on its own line, in a smaller, muted gray, under your links. The Line, Stack, Mark and Portrait layouts show it, and so does the plain-text version. Compact, the one-line layout, leaves it out.
- Click "Copy signature" and paste it into your mail app.
Leave the field empty and there is no address line.
For a company: one address for everyone
On the Company plan the owner sets the address once on the Company page, and it shows on everyone's signature. Members see it on their signature page but cannot change it, the same as the company name and website. When the address changes, the owner changes it once, and each person gets an email with their updated signature to paste. Zoho Mail updates by itself.
A UK registered-office line can go in the address field, or in the company footnote: one line under every member's and every company AI agent's signature. The footnote comes with larger Company sizes; the pricing page shows which. Either way, check one sent email to see that the whole line arrived.
Your AI assistant gets the saved address
An assistant that sends email for you through Signatoro's API or MCP server gets the address with the rest of your signature. It also gets the address as its own field in sender, with the rule to use only those values, so an assistant asked "where is your office?" has the saved address to quote. The post on AI and made-up contact details covers why that rule exists.
Questions
Is an address required in every email signature?
No. US law asks for a postal address in commercial email, and UK law asks companies for their registered office on business letters. A personal reply to a colleague needs neither.
Should the address go in the signature or the footer?
Your own office address fits the signature, next to your phone. A legal line that is the same for everyone, such as a registered office with the company number, fits a footer under the signature. The post on email footer examples has address and registration lines to copy.
Does a long address break the layout on phones?
A single line wraps on a narrow screen like any other text. Keep it to street, city and postal code, and leave out the country if you only write within your own.
Do I need the address on replies too?
When the reply is commercial email in the US, the rule applies to it too. Gmail and Outlook can leave the signature off replies, so check your setting if you rely on the signature to carry the address.
Sources
Read on November 2, 2026: