How to reply from a custom domain address in Gmail — without Google Workspace

The problem: receiving is solved, replying isn’t

Getting domain email into Gmail is straightforward. Cloudflare Email Routing, ImprovMX, and similar tools handle it for free — set up MX records, configure forwarding rules, and mail to support@yourdomain.com shows up in your Gmail inbox.

Replying is the problem. When you hit reply in Gmail, it defaults to your Gmail address. Your customer, who wrote to support@yourdomain.com, receives a reply from yourname@gmail.com.

This guide covers how to fix that, and what each fix costs as your address count grows.

Option 1: Gmail’s built-in Send As

Under Settings → Accounts → Send mail as, you can add support@yourdomain.com and configure it to send through an SMTP server. Options include your domain registrar’s SMTP, or a service like Brevo or Mailjet that has free tiers.

Once configured, Gmail lets you pick the sender address manually when composing or replying. This works fine for one or two addresses on a single domain.

• Free with most registrars or free-tier SMTP services
• You pick the sender address manually from a dropdown
• Each address needs its own SMTP credential
• Gmail doesn’t auto-match the reply sender to the original recipient

Where Send As breaks down

The manual selection step is where this starts to feel fragile. Gmail doesn’t know which address the customer originally wrote to — you have to remember and pick it yourself.

Two addresses is manageable. With support@, billing@, sales@, and hello@ across two or three domains, every reply is a risk. Reply from the wrong address, or from your Gmail instead of the domain — that’s a professional mistake that’s easy to make.

Each new address also means another SMTP credential, another verification flow, another entry in Gmail’s settings.

Option 2: Google Workspace

Workspace gives each domain address its own full Gmail mailbox. You log in, compose, and reply — and everything works because the address is a proper Gmail account.

Cost: around $6 per user per month at the lowest tier. If your “user” is a role address like support@ or billing@, you’re paying a per-person price for what’s functionally just a routing decision.

For large teams with real people behind each address, Workspace is the obvious choice. For small teams managing many addresses, the per-seat cost adds up fast.

Option 3: A relay layer with one shared gateway in Gmail

A relay layer sits between your domain addresses and your Gmail inbox. Inbound works the same as basic forwarding — Cloudflare Email Routing forwards domain mail to Gmail. The difference is what happens next: the relay layer remembers which address the customer wrote to.

When you reply through a single gateway configured in Gmail, the relay reads that information and restores the correct domain address on delivery. Gmail still asks you to use the gateway in the From field, but you no longer need a separate SMTP setup for every address.

OhRelay works this way. One SMTP setup in Gmail covers all your addresses. Support@ customers get replies from support@. Billing@ gets billing@. You choose the same gateway in Gmail, and OhRelay takes care of the visible domain identity behind it.

• One SMTP credential in Gmail, regardless of address count
• One shared gateway in Gmail instead of one SMTP setup per address
• New addresses don’t require new SMTP setup
• Sent copies stay in your Gmail — not stored by OhRelay

Which option fits your situation

One domain, one or two addresses: Send As is fine. Manual selection is a small inconvenience at that scale.

Each address has a real person behind it, and you need the full Google suite: Workspace is the right choice.

Multiple domains, growing address count, small team handling it all: A relay layer removes the daily friction and error risk without a per-address cost.