When one company sends email from several domains, every message has to carry the right brand. A sales rep at brandtwo.com should never send an email with Brand One's logo, address or legal footer under it.
To manage email signatures across multiple domains, create one signature template per domain or brand, assign it to the group that holds that domain's users, and fill in names and job titles from your Google Workspace or Microsoft 365 directory. Give each legal entity its own disclaimer, and add every new domain to your signature setup.
When do you need a different email signature for each domain?
Multi-domain email signature management means controlling the signatures of every domain, brand and subsidiary in one company from a single place, so each email carries the right logo, contact details and legal footer for the address it is sent from.
Most companies start with one domain and one signature. That breaks as soon as the company grows in any of these ways:
- Secondary domains. A second domain for a new product, region or brand, with its own users.
- Multiple brands. One group, several customer-facing brands, each with its own logo, colors and website.
- Subsidiaries. Separate legal entities that each need their own registered name, address and disclaimer.
- Mergers and rebrands. An acquired company keeps its domain for a while, then moves to the new brand on a set date.
In each case the problem is the same: the right people need the right signature, and it has to stay right as people join, leave and change roles.
How Google Workspace handles signatures for multiple domains
Google Workspace has no built-in way to give each domain a designed signature. The closest tool is the admin footer.
An admin can add a standard footer to outgoing emails for an organizational unit (OU). Google's documentation sets these limits:
- The footer applies per OU, and child OUs inherit it. If users from two domains sit in the same OU, they get the same footer.
- It can be up to 10,000 characters, with basic formatting. You can't edit it as HTML.
- Images only work from a public web URL. Images stored in Google Drive aren't allowed.
- Changes can take up to 24 hours to apply.
The footer is added to outgoing mail, so it works for a shared disclaimer. It is not a per-person signature with each user's name, title and phone number. For that, users set their own signature in Gmail, one person at a time.
If your second domain is set up as a user alias domain or a secondary domain, that choice matters. With a secondary domain, users have separate accounts on that domain. With an alias domain, every user simply gets a matching address on the second domain. Google's FAQ for multiple domains explains both.
How Microsoft 365 handles signatures for multiple domains
Microsoft 365 admins can create organization-wide signatures and disclaimers with mail flow rules in the Exchange admin center. A rule can apply to all messages or to messages that meet conditions you set.
Microsoft lists these limits for signatures added this way:
- Users can't see the signature in their Sent Items folder.
- The signature can't be placed directly under the latest reply or forward. It lands at the bottom of the thread.
- Images can't be embedded in the signature.
- If a variable such as a phone number is empty for a user, that line is skipped.
So you can build one rule per domain, but each brand's signature ends up text-heavy, sits below the whole email thread, and is invisible to the person sending it.
How to set up email signatures for multiple domains
The setup below works for any number of domains.
- List what changes per domain. Usually the logo, company name, website, address, phone format and legal disclaimer. Everything else stays the same.
- Group users by domain. In Microsoft 365, create a security group or Microsoft 365 group per domain. New hires then get the right signature as soon as they join the group.
- Build one template for the first domain. Use dynamic fields for name, job title, phone and email, so one template works for everyone on that domain. Upload the domain's logo from a public URL.
- Assign the template to that domain's group or OU.
- Test from a real account. Send to an external address and check Outlook desktop, Outlook on the web, Gmail and a phone.
- Duplicate the template for the next domain. Swap the logo, company details and disclaimer. This is faster than starting from scratch and keeps the layout identical across brands.
Our help centre has the click-by-click version for setting up signatures for different domains in Microsoft 365.
Rolling out to a single domain first? See how to deploy email signatures across your organization.
Four mistakes that put the wrong brand on an email
1. Forgetting about aliases
Signatures follow a person's primary address. If someone's mailbox is on brandone.com but they sometimes send as an alias on brandtwo.com, they will get the Brand One signature on those emails. Give these people a neutral template, or set up their alias separately.
In Google Workspace, BulkSignature can install a signature on an alias only if the user has added it as a "Send as" address in Gmail. Each alias with a signature counts as a separate user for billing. See email aliases and domain aliases.
2. Putting personal signatures on shared mailboxes
Addresses like support@, billing@ or info@ often feed a ticketing tool. A signature with one person's name and photo looks wrong there. Decide on purpose whether each shared mailbox gets a team signature, a plain brand footer or nothing.
3. Adding a domain and forgetting the signature
Adding a new domain in the Microsoft 365 admin center or the Google Admin console doesn't create a signature for it. Make "create the template and the group" part of the checklist every time you register or acquire a domain.
4. Using the wrong legal entity in the footer
Subsidiaries are separate companies. Each one's emails should carry its own registered name and address, and in some countries its registration number. A group-wide disclaimer that names the parent company can be wrong for every subsidiary. Rules differ by country: see what Germany requires in an email signature and the GDPR requirements by country.
How to switch email signatures after a merger or rebrand
A merger or rebrand is a multi-domain problem with a deadline. Use this order:
- Build the new brand's template before announcement day and test it on a few accounts.
- Decide what the acquired company's staff send during the transition: old brand, new brand, or a "now part of" line under the old brand.
- Update the legal entity details in the footer on the date the legal change takes effect, not the marketing date.
- Switch templates for all affected groups at once.
- Add the new domain and its group to the signature setup if staff move to new addresses.
- Check shared mailboxes and aliases separately.
- Keep the old template for 30 days in case you need to roll back.
Server-side vs client-side email signatures
There are two ways a signature tool can add signatures.
- Server-side tools add the signature after the email leaves the sender, as it passes through a mail server. Every message gets it, on any device, but the sender usually can't see it while writing, and it often lands at the bottom of a long thread.
- Client-side tools put the signature into the user's own email client, such as the Gmail signature setting or an Outlook add-in. The sender sees it while writing, and it sits under their latest reply.
For groups with several domains, client-side signatures are easier to check, because each person can see which brand their email is going out with.
Google Workspace and Microsoft 365 vs BulkSignature
| Google Workspace footer | Microsoft 365 mail flow rules | BulkSignature | |
|---|---|---|---|
| One design per domain or brand | Per OU only | One rule per domain | One template per domain, brand or group |
| Personal details per user | No | Variables, empty lines skipped | Pulled from the directory |
| Images and logos | Public URL only | Can't embed images | Yes |
Native sources: Google footer, Microsoft 365 signatures and disclaimers.
When do you need email signature software for multiple domains?
Native tools are enough if you have one domain, a short shared disclaimer, and people are happy to set their own signatures.
You will want a signature tool when any of these is true:
- You run two or more brands or legal entities.
- Each person's signature has to show their own title and phone number, kept current.
- Legal or compliance needs proof that every email carries the right disclaimer.
- You are planning a merger, acquisition or rebrand.
- More than one team (IT, marketing, legal) needs a say in signatures.
How BulkSignature helps
BulkSignature manages every domain's signatures from one dashboard for Google Workspace and Microsoft 365.
- One template per domain or brand, assigned by group, organizational unit or selected users.
- Directory sync fills in each person's name, title, department and phone, and keeps them up to date.
- Template duplication lets you clone the first brand's design and swap the details for the next.
- Email alias support for people who send from more than one address.
- Compliance disclaimers per template, so each entity's legal details stay separate. See the compliance center.
- Role-based permissions so IT, marketing and legal each handle their part.
Setup guides: Microsoft 365 and Google Workspace.
Checklist: is your multi-domain setup right?
- Every domain and brand has its own template.
- Each template is assigned to a group or OU, so new hires get it automatically.
- Personal details come from the directory, not typed by hand.
- Each legal entity's footer shows its own registered details.
- People who send from aliases have the right signature on each address.
- Shared mailboxes have a deliberate signature, or none.
- Adding a domain includes creating its template and group.
- You have tested every brand in Outlook, Gmail and on a phone.
FAQ
Can I have different email signatures for different domains in Microsoft 365?
Yes. With native tools you create a mail flow rule per domain, but Microsoft notes these signatures can't include embedded images, don't show in Sent Items and can't sit under the latest reply. A signature tool lets you build one designed template per domain and assign it by group.
Can Google Workspace set a different signature per domain?
Not as a designed, per-person signature. An admin can add a standard text footer per organizational unit, so if each domain's users sit in their own OU, each can get a different footer. Personal signatures are still set by each user unless you use a signature tool.
What happens when someone sends from an alias on another domain?
The signature follows their primary address, so they get their main domain's signature unless the alias is set up separately. In Gmail, the alias has to be added as a "Send as" address first.
Do subsidiaries need their own email footer?
Usually yes. Each subsidiary is its own legal entity, so its emails should show its own registered name and address, and in some countries its registration number. Check the rules for each country you operate in.
How do I switch email signatures after a merger?
Build and test the new template first, decide what acquired staff send during the transition, update legal details on the date the legal change takes effect, then switch all affected groups at once and keep the old template for 30 days in case you need to roll back.
How do you manage email signatures for multiple companies or brands?
Treat each company or brand as its own template, with its own logo, colors, address and legal footer. Assign each template to the people who send for that brand using groups in Microsoft 365 or Google Workspace, and sync personal details from the directory so one template covers everyone in that brand.
Run every brand from one place
Running more than one brand? Book a demo and we'll set up your first two domains with you, or get started for free.
