In this guide · 7 sections
Short answer
In the Admin console go to Account > Domains > Manage domains > Add a domain. Choose user alias domain if the same people need a second address (free), or secondary domain if the domain has its own users (each paid). Verify with a TXT record, then add MX, SPF and DKIM for that domain.
User alias domain vs secondary domain: which to choose
Google's add a domain guide sets out the difference. The choice depends on whether the new domain has the same people or different people.
User alias domain
Same peopleNo extra cost per user
- Every user gets an extra address, for example ann@newbrand.sg as well as ann@company.sg
- Groups get matching addresses too (info@ at both domains)
- Mail to either address lands in the same inbox
- Up to 20 user alias domains per account
Best for: A second brand, a .sg version of your .com, or a rebrand where you keep the old domain.
Secondary domain
Different peopleEach user is a paid licence
- Separate users, each with their own account and mailbox at that domain
- Managed from the same Admin console
- Can later become the primary domain if you rebrand
- Billing address and company logo stay tied to the primary domain
Best for: A separate business or team that needs its own staff accounts.
Google's multiple domains FAQ confirms the limits: one primary domain plus up to 599 additional domains, of which up to 20 can be domain aliases.
How to add the domain in the Google Admin console
You need the Domain settings administrator privilege, and you must own the domain. If you bought it elsewhere, have your registrar login ready. Google does not accept a domain that contains 'gmail' in its name.
Open Manage domains
In the Google Admin console, go to Menu > Account > Domains > Manage domains.
Click Add a domain
Enter the domain name. If you removed this domain from Workspace recently, wait up to 24 hours before adding it again.
Choose the domain type
Secondary domain if it has its own users or will replace your primary; user alias domain if existing users just need a second address.
Start verification
Click Add domain & start verification and follow the instructions. Most small businesses verify with a TXT record (next section).
Activate Gmail for the domain
Once verified, return to Manage domains, find the new domain and click Activate Gmail. Then add the MX record.
DNS records the new domain needs
Each added domain needs its own DNS records, set at the registrar or DNS host for that domain. They do not inherit anything from your primary domain. If DNS terms are new to you, our plain-English guide to DNS records: A, CNAME, MX and TXT explains each one.
| Record | Type | Value (Google's documented default) | Why |
|---|---|---|---|
| Verification | TXT | The google-site-verification=... value from the Admin console | Proves you own the domain |
| Incoming mail | MX | smtp.google.com, priority 1 | Delivers mail for the domain to Gmail |
| SPF | TXT | v=spf1 include:_spf.google.com ~all | Lists Google as allowed to send for the domain |
| DKIM | TXT | Key generated in Admin console for this domain | Signs mail so receivers can trust it |
| DMARC | TXT at _dmarc | Start with v=DMARC1; p=none; rua=mailto:you@yourdomain | Tells receivers what to do with failing mail |
For MX, Google's MX setup article says to remove any other MX records and allow up to 72 hours for changes to be recognised. If the new domain already receives mail somewhere else, plan the switch; our guide to changing MX records without downtime covers the order of steps.
SPF, DKIM and DMARC for each domain
Mail sent from the new domain is judged on that domain's records, not your primary's. If you skip them, messages from the alias address are more likely to land in spam.
- SPF: if only Google sends for this domain, use the line in the table. If a website, CRM or newsletter tool also sends from it, add their include as well, in one SPF record.
- DKIM: Google's DKIM article says to wait 24 to 72 hours after turning on Gmail before generating the key. Then go to Apps > Google Workspace > Gmail > Authenticate email, pick the new domain in the Selected domain menu, generate a 2048-bit key if your DNS host supports it, add the TXT record and click Start authentication.
- DMARC: Google says you must have SPF and/or DKIM working first. Start at p=none to collect reports, then move to quarantine or reject once legitimate mail passes.
Our guide to SPF, DKIM and DMARC explains how to read the reports and when to tighten the policy.
Sending as the new address in Gmail
With a user alias domain, mail to the new address arrives in the user's existing inbox straight away once MX is live. Sending from it takes one more step, because users still sign in with their primary address.
- In Gmail, click Settings > See all settings > Accounts (or Accounts and Import).
- Under Send mail as, click Add another email address, enter your name and the alias address, and leave Treat as an alias ticked.
- When composing, click the From line and choose the alias. You can also make it the default and set the reply-to address.
Some things always use the primary address: signing in, creating Docs and Drive files, and sending Calendar and sharing invites. If staff need the new domain for everything, that points to a primary domain change or a secondary domain with separate users instead.
Do it yourself or get help?
Adding a user alias domain is a 30-minute job if the domain is new and you are comfortable in your registrar's DNS settings. It gets riskier when the domain already has a website and mail elsewhere, when a website or newsletter tool also sends from it, or when you are unsure which type to pick.
New domain checklist
Our Business Email Setup (S$249) configures the new domain, aliases and authentication records end to end. If you only need the DNS side done, Domain & DNS Setup (S$99) covers the records. New to Workspace altogether? Start with our guide to setting up business email in Singapore.
Frequently asked questions
A user alias domain does not cost extra; every existing user and group simply gets an address at the new domain. A secondary domain is free to add, but each user account you create on it needs its own paid Google Workspace licence, except in Education Fundamentals and Nonprofits editions.
No. Google says users sign in with their primary email address, not the alias. They can receive mail at the alias, add it as a Send mail as address in Gmail and share files with either address, but Docs, Calendar invites and sharing invites always come from the primary address.
Verification completes once Google can see the TXT record, which depends on your DNS host. Google says MX changes can take up to 72 hours to be recognised, and you must wait 24 to 72 hours after activating Gmail before generating the DKIM key. Plan for a few days before relying on the new address.
Yes. SPF, DKIM and DMARC are published per domain, so the new domain needs its own SPF record, its own DKIM key generated for that domain in the Admin console, and its own DMARC record. Without them, mail sent from the alias address is more likely to fail checks and land in spam.
Yes, depending on your Google Workspace account type. Google's help pages describe changing the primary domain, and adding the new domain as a secondary domain first is the recommended route if you plan to replace the primary. Check billing, the company logo and any services tied to the old primary before switching.